ios - 为什么 swift 中的 var++ 是错误的，而改成 var+1 是正确的

Question

初学swift，为什么第一个错了？ 谢谢~~ˊ_>ˋ

Answer 1

应该是currentAudioIndex++(没有空格)。它等同于:currentAudioIndex = (currentAudioIndex)%2

currentAudioIndex = (currentAudioIndex++)%2 
// plus 1 to currentAudioIndex will be overrided by `currentAudioIndex =`.
// With (currentAudioIndex++)%2. E.g currentAudioIndex = 1
// 1. currentAudioIndex return 1 for the operator %. It's "1%2"
// 2. currentAudioIndex plus 1. currentAudioIndex == 2 now.
// 3. The operator % (1%2) return 1 for currentAudioIndex.
// 4. currentAudioIndex == 1  at the end.

但在你的情况下，我认为你想要这个 ++currentAudioIndex。它与

相同

currentAudioIndex = currentAudioIndex + 1
currentAudioIndex = (currentAudioIndex)%2