我看着Xcode 7.3笔记，我注意到这个问题。
The ++ and — operators have been deprecated
有人能解释为什么它被废弃？我是对的，在新版本的Xcode现在你要使用，而不是这个x = 1;
例：
for var index = 0; index < 3; index += 1 {
print("index is (index)")
}
来自Chris Lattner的
full explanation here，Swift的创作者。我将总结几点：
>这是另一个功能，你必须学习，而学习Swift
>不比x = 1短得多
> Swift不是C.不应该携带他们只是为了请C程序员
>它主要用于C型for循环：for i = 0; i< n; i {...}，其中Swift有更好的替代方案，例如对于i in 0 ..< n {...}(C风格for循环是going out as well)
>可能难以阅读和维护，例如，x – x或foo(x，x)的值是什么？
>克里斯·拉特纳不喜欢它。
对于那些感兴趣的人(为了避免链接腐烂)，Lattner用他自己的话说的原因是：
-
These operators increase the burden to learn Swift as a first programming language – or any other case where you don’t already know these operators from a different language.
-
Their expressive advantage is minimal – x++ is not much shorter than x += 1.
-
Swift already deviates from C in that the =,+= and other assignment-like operations returns Void (for a number of reasons). These operators are inconsistent with that model.
-
Swift has powerful features that eliminate many of the common reasons you’d use ++i in a C-style for loop in other languages,so these are relatively infrequently used in well-written Swift code. These features include the for-in loop,ranges,enumerate,map,etc.
-
Code that actually uses the result value of these operators is often confusing and subtle to a reader/maintainer of code. They encourage “overly tricky” code which may be cute,but difficult to understand.
-
While Swift has well defined order of evaluation,any code that depended on it (like foo(++a,a++)) would be undesirable even if it was well-defined.
-
These operators are applicable to relatively few types: integer and floating point scalars,and iterator-like concepts. They do not apply to complex numbers,matrices,etc.
Finally,these fail the metric of “if we didn’t already have these,would we add them to Swift 3?”
（编辑：李大同）
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