Ios Swift:NSError作为NSErrorPointer传递始终为零
我正试图实现苹果Swift文档()中“错误报告”部分所述的错误处理,但我肯定遗漏了什么 我有下面的代码(简化),即使网络请求明显失败(我与internet断开连接,并且“ERROR”被打印出来),我作为指针传递的错误变量在完成块内始终为零 我做错了什么?谢谢Ios Swift:NSError作为NSErrorPointer传递始终为零,ios,swift,nserror,Ios,Swift,Nserror,我正试图实现苹果Swift文档()中“错误报告”部分所述的错误处理,但我肯定遗漏了什么 我有下面的代码(简化),即使网络请求明显失败(我与internet断开连接,并且“ERROR”被打印出来),我作为指针传递的错误变量在完成块内始终为零 我做错了什么?谢谢 override func viewDidLoad() { super.viewDidLoad() var error: NSError? // THIS IS ACTUALLY IN ANOTHER CLAS
override func viewDidLoad() {
super.viewDidLoad()
var error: NSError?
// THIS IS ACTUALLY IN ANOTHER CLASS,
// BUT EVEN IF PLACED IN THE SAME CLASS I STILL GET THE SAME PROBLEM
doStuff({ (result) -> Void in
println("\(error)") // THIS PRINTS NIL
}, errorPointer: &error)
}
func doStuff(completion: (result:SomeType) -> Void, errorPointer: NSErrorPointer) {
// SETUP CODE NOT INCLUDED
let downloadTask = manager.downloadTaskWithRequest(req, progress: nil, destination: { (url, response) -> NSURL! in
return destinationURL
}) { (response, url, error) -> Void in
// CREATE RESULT
if(error != nil && errorPointer != nil) {
println(“ERROR”) // THIS GETS PRINTED
errorPointer.memory = error // ALSO TRIED NSError(...)
}
completion(result)
}
downloadTask.resume()
}
解决方案 你会在苹果免费电子书《使用Swift与Cocoa和Objective-C》中找到一个关于Swift错误处理的清晰例子(第51页) 基本上,您希望查看错误的内存地址,然后测试该值以处理错误。尝试从中推断并重写代码以获得有效的结果 此外,如果必须使用NSErrorPointer,请参见以下内容
var writeError: NSError?
let written = myString.writeToFile(path, atomically: false,
encoding: NSUTF8StringEncoding,
error: &writeError)
if !written {
if let error = writeError {
println("write failure: \(error.localizedDescription)")
}
}
Excerpt From: Apple Inc. “Using Swift with Cocoa and Objective-C.” iBooks. https://itun.es/us/1u3-0.l