ios - Swift:访问通过post请求收到的JSON

Question

    let task = URLSession.shared.dataTask(with: postRequest) { data, response, error in
        guard let data = data, error == nil else {
            print(error?.localizedDescription ?? "NoData")
            return
        }
        let jsonString = String(data: data, encoding: String.Encoding.utf8)!
        self.submitView.text = jsonString
    }
    task.resume()

我正在尝试访问此发布请求的返回值。我设置了一个断点，发现 jsonString 确实获得了正确的值。但是，当我尝试将 self.submitView.text 设置为任何内容时，我收到此错误:

2017-06-21 14:20:16.062815-0400 Button[958:197756] This application is modifying the autolayout engine from a background thread after the engine was accessed from the main thread. This can lead to engine corruption and weird crashes.
 Stack:(
    0   CoreFoundation                      0x0000000191c82ff8 <redacted> + 148
    1   libobjc.A.dylib                     0x00000001906e4538 objc_exception_throw + 56
    2   CoreFoundation                      0x0000000191c82f28 <redacted> + 0
    3   Foundation                          0x0000000192874338 <redacted> + 128
    4   Foundation                          0x00000001926bc9f8 <redacted> + 36
    5   UIKit                               0x0000000197daf76c <redacted> + 816
    6   UIKit                               0x0000000197dbb668 <redacted> + 1740
    7   UIKit                               0x0000000197dbaf84 <redacted> + 828
    8   UIKit                               0x0000000197df90f4 <redacted> + 256
    9   UIKit                               0x0000000197df1818 <redacted> + 116
    10  UIKit                               0x00000001987ec308 <redacted> + 48
    11  UIKit                               0x0000000197e5d880 <redacted> + 280
    12  UIFoundation                        0x0000000197cdb238 <redacted> + 7012
    13  UIFoundation                        0x0000000197cdc0c8 <redacted> + 52
    14  UIFoundation                        0x0000000197d0eb70 <redacted> + 48
    15  UIKit                               0x0000000197e5d85c <redacted> + 244
    16  UIFoundation                        0x0000000197ce0214 <redacted> + 2172
    17  UIFoundation                        0x0000000197d0b058 <redacted> + 240
    18  UIFoundation                        0x0000000197d2f474 <redacted> + 160
    19  UIFoundation                        0x0000000197d2ebb4 <redacted> + 92
    20  UIKit                               0x0000000197e60500 <redacted> + 252
    21  UIKit                               0x0000000197e603e4 <redacted> + 196
    22  Button                              0x0000000100061e24 _TFFC6Button14ViewController12submitTappedFT_T_U_FTGSqV10Foundation4Data_GSqCSo11URLResponse_GSqPs5Error___T_ + 784
    23  Button                              0x0000000100062468 _TTRXFo_oGSqV10Foundation4Data_oGSqCSo11URLResponse_oGSqPs5Error____XFdCb_dGSqCSo6NSData_dGSqS1__dGSqCSo7NSError___ + 224
    24  CFNetwork                           0x000000019228c34c <redacted> + 32
    25  CFNetwork                           0x00000001922a4048 <redacted> + 148
    26  Foundation                          0x0000000192751814 <redacted> + 16
    27  Foundation                          0x0000000192696770 <redacted> + 96
    28  Foundation                          0x0000000192686b28 <redacted> + 612
    29  Foundation                          0x0000000192753bb0 <redacted> + 228
    30  libdispatch.dylib                   0x0000000100a6da10 _dispatch_client_callout + 16
    31  libdispatch.dylib                   0x0000000100a7b2e8 _dispatch_queue_serial_drain + 1140
    32  libdispatch.dylib                   0x0000000100a71634 _dispatch_queue_invoke + 852
    33  libdispatch.dylib                   0x0000000100a7d630 _dispatch_root_queue_drain + 552
    34  libdispatch.dylib                   0x0000000100a7d39c _dispatch_worker_thread3 + 140
    35  libsystem_pthread.dylib             0x0000000190d43100 _pthread_wqthread + 1096
    36  libsystem_pthread.dylib             0x0000000190d42cac start_wqthread + 4
)
2017-06-21 14:20:16.085280-0400 Button[958:197756] This application is modifying the autolayout engine from a background thread after the engine was accessed from the main thread. This can lead to engine corruption and weird crashes.
 Stack:(
    0   CoreFoundation                      0x0000000191c82ff8 <redacted> + 148
    1   libobjc.A.dylib                     0x00000001906e4538 objc_exception_throw + 56
    2   CoreFoundation                      0x0000000191c82f28 <redacted> + 0
    3   Foundation                          0x0000000192874338 <redacted> + 128
    4   Foundation                          0x00000001926bc9f8 <redacted> + 36
    5   UIKit                               0x0000000197eb18e0 <redacted> + 564
    6   UIKit                               0x0000000197db0138 <redacted> + 224
    7   UIKit                               0x0000000197daf8d0 <redacted> + 120
    8   Foundation                          0x00000001926bca7c <redacted> + 168
    9   UIKit                               0x0000000197daf76c <redacted> + 816
    10  UIKit                               0x0000000197dbb668 <redacted> + 1740
    11  UIKit                               0x0000000197dbaf84 <redacted> + 828
    12  UIKit                               0x0000000197df90f4 <redacted> + 256
    13  UIKit                               0x0000000197df1818 <redacted> + 116
    14  UIKit                               0x00000001987ec308 <redacted> + 48
    15  UIKit                               0x0000000197e5d880 <redacted> + 280
    16  UIFoundation                        0x0000000197cdb238 <redacted> + 7012
    17  UIFoundation                        0x0000000197cdc0c8 <redacted> + 52
    18  UIFoundation                        0x0000000197d0eb70 <redacted> + 48
    19  UIKit                               0x0000000197e5d85c <redacted> + 244
    20  UIFoundation                        0x0000000197ce0214 <redacted> + 2172
    21  UIFoundation                        0x0000000197d0b058 <redacted> + 240
    22  UIFoundation                        0x0000000197d2f474 <redacted> + 160
    23  UIFoundation                        0x0000000197d2ebb4 <redacted> + 92
    24  UIKit                               0x0000000197e60500 <redacted> + 252
    25  UIKit                               0x0000000197e603e4 <redacted> + 196
    26  Button                              0x0000000100061e24 _TFFC6Button14ViewController12submitTappedFT_T_U_FTGSqV10Foundation4Data_GSqCSo11URLResponse_GSqPs5Error___T_ + 784
    27  Button                              0x0000000100062468 _TTRXFo_oGSqV10Foundation4Data_oGSqCSo11URLResponse_oGSqPs5Error____XFdCb_dGSqCSo6NSData_dGSqS1__dGSqCSo7NSError___ + 224
    28  CFNetwork                           0x000000019228c34c <redacted> + 32
    29  CFNetwork                           0x00000001922a4048 <redacted> + 148
    30  Foundation                          0x0000000192751814 <redacted> + 16
    31  Foundation                          0x0000000192696770 <redacted> + 96
    32  Foundation                          0x0000000192686b28 <redacted> + 612
    33  Foundation                          0x0000000192753bb0 <redacted> + 228
    34  libdispatch.dylib                   0x0000000100a6da10 _dispatch_client_callout + 16
    35  libdispatch.dylib                   0x0000000100a7b2e8 _dispatch_queue_serial_drain + 1140
    36  libdispatch.dylib                   0x0000000100a71634 _dispatch_queue_invoke + 852
    37  libdispatch.dylib                   0x0000000100a7d630 _dispatch_root_queue_drain + 552
    38  libdispatch.dylib                   0x0000000100a7d39c _dispatch_worker_thread3 + 140
    39  libsystem_pthread.dylib             0x0000000190d43100 _pthread_wqthread + 1096
    40  libsystem_pthread.dylib             0x0000000190d42cac start_wqthread + 4
)
2017-06-21 14:20:16.088842-0400 Button[958:197756] *** Assertion failure in void _UIPerformResizeOfTextViewForTextContainer(NSLayoutManager *, UIView<NSTextContainerView> *, NSTextContainer *, NSUInteger)(), /BuildRoot/Library/Caches/com.apple.xbs/Sources/UIFoundation/UIFoundation-491.7/UIFoundation/TextSystem/NSLayoutManager_Private.m:1577
2017-06-21 14:20:16.089727-0400 Button[958:197756] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Only run on the main thread!'
*** First throw call stack:
(0x191c82fe0 0x1906e4538 0x191c82eb4 0x19271a78c 0x197cd93f8 0x197cd90d8 0x197d07e88 0x197d0b188 0x197d2f474 0x197d2ebb4 0x197e60500 0x197e603e4 0x100061e24 0x100062468 0x19228c34c 0x1922a4048 0x192751814 0x192696770 0x192686b28 0x192753bb0 0x100a6da10 0x100a7b2e8 0x100a71634 0x100a7d630 0x100a7d39c 0x190d43100 0x190d42cac)
libc++abi.dylib: terminating with uncaught exception of type NSException

似乎我无法将 self.submitView.text 分配给“任务”范围内的任何内容。有什么想法吗？

编辑:这是服务器在发送请求时返回的内容。

"{\"raw\":\"约翰星期一在纽约的日程\",\"地点\":\"纽约\",\"日期\":\"星期一, 6 月 26 日\",\"name\":\"john\",\"errorResponse\":null,\"stripTest\":\"星期一约翰在纽约\"}"

这就是我的代码:

做{
让 info = 尝试 JSONSerialization.jsonObject(with: data, options: .allowFragments) 作为？ [字符串:任意]
DispatchQueue.main.async {
self.submitView.text = info?["name"] as!字符串
}
} 捕获 {
DispatchQueue.main.async {
self.submitView.text = "错误"
}
}

“ERROR”不再打印，但“info”似乎有 0 个键/值对，因此不会打印任何内容。

更新:

print(try? JSONSerialization.jsonObject(with: data, options: [])) 打印“nil”

后者打印:

Optional("\"{\\\"raw\\\":\\\"Schedule for John in New York on Monday\\\",\\\"location\\\":\\\"new york\\\",\\\"date\\\":\\\"6/26/2017 12:00:00 AM\\\",\\\"name\\\":\\\"john\\\",\\\"errorResponse\\\":null,\\\"stripTest\\\":\\\" for john in new york on monday \\\"}\"")

当我将它分配给 UI 中的 TextView 时，这不是打印的内容。它会将转义序列转换为文字字符吗？

Answer 1

您正在后台线程上设置 UITextField 的文本属性。

您需要确保所有 UI 工作都在主线程上完成，您可以使用 DispatchQueue 来完成此操作...

DispatchQueue.main.async {
    self.submitView.text = jsonString
}

更新:

数据实际上是通过网络发送的数据，您需要对其进行转换和反序列化。

您可以使用 JSON Serialisation class 来执行此操作像这样:

// I create some dummy JSON string for example purposes
let data = "{ \"name\": \"John Smith\"}".data(using: String.Encoding.utf8)!

if let jsonObject = try JSONSerialization.jsonObject(with: data, options: .allowFragments) as? [String:AnyObject] {
    print(jsonObject["name"] as! String)
}

这会尝试将数据转换为 JSON 对象，在 Swift 中通常会转换为字典对象。

有大量关于 Swift 网络的资源可供使用。我强烈推荐的一个是 iOS Networking with Swift这将需要相当多的时间来完成和学习，所以这里有一些可以更快完成的东西Working with JSON in Swift

更新

这段代码对我有用:

let data = "{\"raw\":\"schedule for John in New York on Monday\",\"location\":\"New York\",\"date\":\"Mon, June 26\",\"name\":\"john\",\"errorResponse\":null,\"stripTest\":\"for John in new york on Monday\"}".data(using: String.Encoding.utf8)!

if let jsonObject = try JSONSerialization.jsonObject(with: data, options: .allowFragments) as? [String:AnyObject] {
    print(jsonObject)
    print(jsonObject["name"] as! String)
}