Archive of category 'Swift fundamentals'
- 
        
          Aug 27, 2019
          
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        Swift fundamentals
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
  
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        swift,
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
  
    
    
      
    
      
    
      
    
      
    
      
    
      
    
      
        iOS,
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
  
    
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
        type casting
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
  
          
          
        
        Swift bit #4 - Swifty ways of typecasting objects
- 
        
          Aug 3, 2019
          
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        Swift fundamentals
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
  
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        swift,
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
  
    
    
      
    
      
        for loops,
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
  
    
    
      
    
      
    
      
        for in loops,
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
  
    
    
      
    
      
    
      
    
      
        unwrap,
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
  
    
    
      
    
      
    
      
    
      
    
      
        optionals
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
  
          
          
        
        Swift bit #3 — Unwrap optional values using for in loop
- 
        
          Aug 1, 2019
          
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        Swift fundamentals
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
  
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        swift,
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
  
    
    
      
    
      
        for loops,
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
  
    
    
      
    
      
    
      
        for in loops,
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
  
    
    
      
    
      
    
      
    
      
        unwrap,
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
  
    
    
      
    
      
    
      
    
      
    
      
        optionals
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
      
    
  
          
          
        
        Swift bit #1 — Using “where” clause in “for in” loops