#warning：C 风格的 for 语句已弃用，将在 Swift 的未来版本中删除

Question

我刚刚下载了一个新的 Xcode (7.3) 和 swift 2.2.

它有一个警告：

C-style for statement is deprecated and will be removed in a future version of Swift.

如何修复此警告？

Answer 1

删除 for init; comparison; increment {} 并轻松删除 ++ 和 --。并使用 Swift 漂亮的 for-in 循环

   // WARNING: C-style for statement is deprecated and will be removed in a future version of Swift
   for var i = 1; i <= 10; i += 1 {
      print("I'm number \(i)")
   }

Swift 2.2:

   // new swift style works well
   for i in 1...10 {
      print("I'm number \(i)")
   }

用于递减索引

  for index in 10.stride(to: 0, by: -1) {
      print(index)
  }

或者您可以像

一样使用 reverse()

  for index in (0 ..< 10).reverse() { ... }

对于浮点型 (there is no need to define any types to index)

 for index in 0.stride(to: 0.6, by: 0.1) {
     print(index)  //0.0 ,0.1, 0.2,0.3,0.4,0.5
 }

Swift 3.0:

从Swift3.0开始，Strideable上的stride(to:by:)方法已经替换为一个自由函数，stride(from:to:by:)

for i in stride(from: 0, to: 10, by: 1){
    print(i)
}

对于Swift 3.0中的递减索引，可以使用reversed()

for i in (0 ..< 5).reversed() {
    print(i) // 4,3,2,1,0
}

除了for each和stride()，您可以使用While Loops

var i = 0
while i < 10 {
    i += 1
    print(i)
}

Repeat-While Loop:

var a = 0
repeat {
   a += 1
   print(a)
} while a < 10

查看 The Swift Programming Language Guide

中的控制流

Answer 2

我在这段代码中遇到了同样的错误：

for (var i = 1; i != video.getAll().count; i++) {
    print("show number \(i)")
}

当你尝试用 Xcode 修复它时，你没有运气......所以你需要使用新的 swift 样式（for in loop）：

for i in 1...video.getAll().count {
    print("show number \(i)")
}

Answer 3

Blockquote

改用这个

if(myarr.count)
{
    for i in 1...myarr?.count {
      print(" number is \(i)")
    }
}

Answer 4

对于这种"for"循环：

for var i = 10; i >= 0; --i {
   print(i)
}

你可以这样写：

for i in (0...10).reverse() {
    print(i)
}

#warning：C 风格的 for 语句已弃用，将在 Swift 的未来版本中删除

#warning: C-style for statement is deprecated and will be removed in a future version of Swift

ios

objective-c

swift

swift2.2