修复了警告“C语言对于语句已被弃用”在Swift 3

问题描述

我将 Xcode 更新为7.3，现在我对用于创建随机字符串的函数发出警告。

我试图用来替换语句中的（我在0 ..< len）{...} code>然而，警告成了一个错误。

我怎样才能删除警告？

  static func randomStringWithLength（len：Int） - > NSString {
 let letters：NSString =abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789
 let randomString：NSMutableString = NSMutableString（capacity：len）
 
 for（var i = 0; i< len; i + = 1）{//警告
 let length = UInt32（letters.length）
 let rand = arc4random_uniform（length）
 randomString.appendFormat（％C，letters.characterAtIndex（Int （rand）））
} 
 return randomString 
} 
  

解决方案

我还没有找到一种方法来抑制Swift中的单个警告消息。你可以压制一切，这是一个坏主意。

您可以将您的循环重写为Swift风格：

<$ p $ lt;
let length = UInt32（letters.length）
let rand = arc4random_uniform（length）
randomString.appendFormat （％C，letters.characterAtIndex（Int（rand）））
}

由于您在循环体内根本不使用 i ，所以您可以将其替换为：

  for _ in 0 ..< len {
 // do stuffs 
} 
  

I have update Xcode to 7.3 and now I have a warning to the function that I use to create random strings.

I have tried to change the for statement with for (i in 0 ..< len){...} however, the warning became an error.

How can I remove the warning?

static func randomStringWithLength (len : Int) -> NSString {
  let letters : NSString = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
  let randomString : NSMutableString = NSMutableString(capacity: len)

  for (var i=0; i < len; i += 1){ // warning
    let length = UInt32 (letters.length)
    let rand = arc4random_uniform(length)
    randomString.appendFormat("%C", letters.characterAtIndex(Int(rand)))
  }
  return randomString
}

解决方案

I haven't found a way to suppress a single warning message in Swift. You can suppress everything, which is a bad idea.

You can rewrite your loop to Swift's style:

for i in 0..<len {
    let length = UInt32 (letters.length)
    let rand = arc4random_uniform(length)
    randomString.appendFormat("%C", letters.characterAtIndex(Int(rand)))
}

Since you don't use i at all in the loop's body, you can replace it with:

for _ in 0..<len {
    // do stuffs
}

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