ios - Swift 函数无法尝试从 rest 服务获取 JSON 数组并转换为 swift 对象

Question

我正在尝试从 REST 端点获取数据并将其转换为一些我可以获得 JSON 的各个属性的对象。

这是我目前的方法:

func getUpcoming(callback: (NSDictionary?, String?) -> Void) {

        println("In get upcoming")

        var request = NSMutableURLRequest(URL: NSURL(string: Constants.makeUrl("/events")))
        request.HTTPMethod = "GET"
        request.addValue("application/json", forHTTPHeaderField: "Content-Type")
        request.addValue("application/json", forHTTPHeaderField: "Accept")
        request.addValue("Bearer 6cfee427-2134-4ba7-89c0-8dbfda2ce6b4", forHTTPHeaderField: "Authorization")

        var session = NSURLSession.sharedSession()
        var task = session.dataTaskWithRequest(request) {
            (data, response, error) -> Void in

            println("data = \(data)")
            println("response = \(response)")
            println("error = \(error)")

            if error != nil {
                callback(nil, error.localizedDescription)
            } else {
                var result = NSString(data: data, encoding: NSASCIIStringEncoding)
                println("result = \(result)")

                let newData: NSData = data
                println("before")
                var upcomingEvents: NSDictionary = NSJSONSerialization.JSONObjectWithData(newData, options: NSJSONReadingOptions.AllowFragments, error: nil) as NSDictionary
                println("after") // NEVER GETS HERE

                callback(upcomingEvents, nil)
            }

        }
        task.resume()
    }

这是一些 println 输出:

...
error = nil
result = [{"id":1912,"name":"Game VS Larson Siding/Kathys Pub","team_id":265,"timezone":"America/Chicago","start":"2015-11-18T20:00:21.000-06:00","end":"2015-11-18T21:00:21.000-06:00","description":null,"location":"Court C","default_response":{"id":1,"label":"No Response"}},{"id":1887,"name":"Lunch Broomball","team_id":29,"timezone":"America/Chicago","start":"2015-11-20T11:15:22.000-06:00","end":"2015-11-20T13:00:22.000-06:00","description":"Be there on the ice at 11:20 for warmup.  Games start at 11:30","location":"Graham 4","default_response":{"id":1,"label":"No Response"}},{"id":1892,"name":"Game #5 vs. Cunnilinguys (Goaltender: Zane)","team_id":327,"timezone":"America/Chicago","start":"2015-11-22T10:00:17.000-06:00","end":"2015-11-22T11:00:17.000-06:00","description":null,"location":"Dodge County Ice Arena, Kasson","default_response":{"id":1,"label":"No Response"}}]
before

这是我屏幕上弹出的内容，我从未在我的控制台中收到实际异常。

libswiftCore.dylib`swift_dynamicCastObjCClassUnconditional:
0x107b98980:  pushq  %rbp
0x107b98981:  movq   %rsp, %rbp
0x107b98984:  pushq  %rbx
0x107b98985:  pushq  %rax
0x107b98986:  movq   %rsi, %rcx
0x107b98989:  movq   %rdi, %rbx
0x107b9898c:  xorl   %eax, %eax
0x107b9898e:  testq  %rbx, %rbx
0x107b98991:  je     0x107b989ac               ; swift_dynamicCastObjCClassUnconditional + 44
0x107b98993:  movq   0x7f236(%rip), %rsi       ; "isKindOfClass:"
0x107b9899a:  movq   %rbx, %rdi
0x107b9899d:  movq   %rcx, %rdx
0x107b989a0:  callq  0x107b9b46a               ; symbol stub for: objc_msgSend
0x107b989a5:  testb  %al, %al
0x107b989a7:  movq   %rbx, %rax
0x107b989aa:  je     0x107b989b3               ; swift_dynamicCastObjCClassUnconditional + 51
0x107b989ac:  addq   $0x8, %rsp
0x107b989b0:  popq   %rbx
0x107b989b1:  popq   %rbp
0x107b989b2:  retq   
0x107b989b3:  leaq   0xc158(%rip), %rax        ; "Swift dynamic cast failed"
0x107b989ba:  movq   %rax, 0x87427(%rip)       ; gCRAnnotations + 8
0x107b989c1:  int3   
0x107b989c2:  nopw   %cs:(%rax,%rax)

我是一名敏捷(和 iOS 开发)新手。请帮忙。

Answer 1

您的结果值是一个数组，如您在方括号中所见。错误是告诉你你在这一行中的类型转换

var upcomingEvents: NSDictionary = NSJSONSerialization.JSONObjectWithData(newData, options: NSJSONReadingOptions.AllowFragments, error: nil) as NSDictionary

无法将结果转换为类型 NSDictionary。

您可以通过将结果转换为 NSArray(或 [[String : AnyObject]])并获取数组的第一项来获取您要查找的字典。