没有'+ ='候选者产生预期的上下文结果类型'Int' [英] No '+=' candidates produce the expected contextual result type 'Int'

问题描述

我一直在为Swift 3更新我的Swift代码（非常兴奋），到目前为止一直很好。
但我做了一些代码，我似乎无法更新。

I've been updating my Swift code for Swift 3 (really excited) and so far so good. But I did tumble accros one little bit of code I can't seem to update.

我知道我错过了一些非常简单的东西，但我可以看看是什么。

I KNOW I am missing something very simple, but I just can't see what.

以下是我在Swift 2.2中的内容：

Here is what I have in Swift 2.2:

var column = 0

[...]

for item in 0 ..< collectionView!.numberOfItemsInSection(0) {
    [...]

    column = column >= (numberOfColumns - 1) ? 0 : ++column
}

++列当然在Swift 3中被弃用，而不是列+ = 1

The ++column is of course being deprecated in Swift 3 in favor of column += 1

但是，在这种情况下，它产生一个错误：

However, in THIS context, it produces an error:

没有'+ ='候选产生预期的上下文结果类型'Int'

No '+=' candidates produce the expected contextual result type 'Int'

由于这行代码（ column = column> =（numberOfColumns - 1）？0：column + = 1 ）产生错误，我尝试了以下内容：

Since this line of code (column = column >= (numberOfColumns - 1) ? 0 : column += 1) produces an error, I tried the following:

var newCol = column
column = column >= (numberOfColumns - 1) ? 0 : newCol += 1

但我得到同样的错误。

有人能指出我正确的方向吗？

Could someone point me in the correct direction?

推荐答案

+ = 不返回值。你需要打破这个。幸运的是，你的情况比原来简单明了：

+= does not return a value. You need to break this out. Luckily in your case that's straightforward and clearer than the original:

column = (column + 1) % numberOfColumns

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