ios 在 Swift 3 中处理 try 和 throws
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/39751923/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Handling try and throws in Swift 3
提问by KexAri
Before Swift 3 I was using:
在 Swift 3 之前，我使用的是：
guard let data = Data(contentsOf: url) else {
print("There was an error!)
return
}
However I now have to use do, tryand catch. I'm not familiar with this syntax. How would I replicate this behaviour?
但是我现在必须使用do,try和catch. 我不熟悉这种语法。我将如何复制这种行为？
回答by Eric Aya
The difference here is that Data(contentsOf: url)does not return an Optional anymore, it throws.
这里的区别在于Data(contentsOf: url)不再返回 Optional ，而是抛出。
So you can use it in Do-Catch but without guard:
所以你可以在 Do-Catch 中使用它，但没有guard：
do {
let data = try Data(contentsOf: url)
// do something with data
// if the call fails, the catch block is executed
} catch {
print(error.localizedDescription)
}
Note that you could still use guardwith try?instead of trybut then the possible error message is ignored. In this case, you don't need a Do-Catch block:
请注意，您仍然可以使用guardwithtry?而不是，try但可能会忽略可能的错误消息。在这种情况下，您不需要 Do-Catch 块：
guard let data = try? Data(contentsOf: url) else {
print("There was an error!")
// return or break
}
// do something with data
