Swift Tutorial(swift 教程) 1: Welcome to Programming

var@H_301_2@ goofOffTime var@H_301_2@ bossComing 0@H_301_2@(@H_301_2@goofOffTime > "Goofing off!"@H_301_2@)@H_301_2@  goofOffTime =@H_301_2@ goofOffTime 1@H_301_2@  bossComing =@H_301_2@ bossComing (@H_301_2@goofOffTime ==@H_301_2@ bossComing"Done goofing off."@H_301_2@        Continue Statement continue语句  
 continue语句和break语句非常相似，区别在于，continue不是退出整个循环，只是跳出当前这一轮循环，程序回到循环的开始处，然后进行条件的判断是否执行下一轮循环。.
   
   
    
     
 
var@H_301_2@ numbers (@H_301_2@numbers <10@H_301_2@(@H_301_2@numbers 9@H_301_2@{@H_301_2@    numbers =@H_301_2@ numbers 1@H_301_2@    continue@H_301_2@  }@H_301_2@  (@H_301_2@numbers)@H_301_2@  numbers }@H_301_2@
 
    
   
  
  
 
 
"List of World Wars:"@H_301_2@var@H_301_2@ ww 1@H_301_2@(@H_301_2@ww <5@H_301_2@(@H_301_2@ww 3@H_301_2@ || ww 4@H_301_2@{@H_301_2@    ww =@H_301_2@ ww "World War \(@H_301_2@ww)"@H_301_2@)@H_301_2@  ww "That's the beauty of World War V,Lois. It's so intense it skips over the other two. - Peter Griffin"@H_301_2@)@H_301_2@
 .   Optionals可选性 
 有时候会出现不确定变量是有值还是空值的情况。空值表示该变量赋值为nil.
 
 可选性代表变量要么表示为一个值，要么为nil:
   
   
    
     
 
var@H_301_2@ optionalNumberInt@H_301_2@? 5@H_301_2@optionalNumber nil@H_301_2@
 
    
   
  
  
 符号?表示该值是可选的. :
   
   
    
     
 
if@H_301_2@ let@H_301_2@ number =@H_301_2@ optionalNumber
 
    
   
  
  
 if let等同于if.
        
    
     
      
 
=@H_301_2@ optionalNumber  "It is a number"@H_301_2@"It is not a number"@H_301_2@}@H_301_2@
               
 @H_301_2@        
     
    
   
            Conversion Between Data Types数据类型的转换 
 Optionals 在变量的类型转换上很有用. 下面的例子是将String转换为Int.
   
   
    
     
 
var@H_301_2@ languagesLearned"3"@H_301_2@var@H_301_2@ languagesLearnednum=@H_301_2@ languagesLearned.toInt(@H_301_2@ 这里声明了一个初值为@H_301_2@"3"的字符串变量@H_301_2@languagesLearned,以及一个可选变量languagesLearnednum并调用函数toInt().给其赋初值 。Methods are very similar to functions likeprintln()that you learned earlIEr,except that they are a part of aclass. You will learn more about that later.
 
toInt()同println()@H_301_2@方法一样都是已经实现了的，是一个类的一部分，这个在后面会学到更多。 该方法是将String以Int类型输出. 之所以将languagesLearnednum声明为可选性，是因为它的值有可能是nil. 比如你要转换的字符串不包含数字，而是像"Hello,World".
 
 输入下面的代码:
   
   
    
     
 
let@H_301_2@ num =@H_301_2@ languagesLearnednum   
 
   
var@H_301_2@ tutorialTeam"55"@H_301_2@var@H_301_2@ editorialTeam 23@H_301_2@var@H_301_2@ tutorialTeamNum=@H_301_2@ tutorialTeam.toInt)@H_301_2@let@H_301_2@ numTutorial =@H_301_2@ tutorialTeamNum  (@H_301_2@numTutorial > editorialTeam{@H_301_2@    \(@H_301_2@numTutorial) is greater than \(@H_301_2@editorialTeam)"@H_301_2@)@H_301_2@  (@H_301_2@numTutorial < editorialTeam\(@H_301_2@numTutorial) is less than \(@H_301_2@numTutorial) is equal to "InvalID entry"@H_301_2@}@H_301_2@
 
 
 
 
 
 
 
 
 
http://www.raywenderlich.com/75919/learn-to-code-ios-apps-with-swift-tutorial-1 @H_301_2@
          总结       
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