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()
我试图访问此帖子请求的返回值。我设置了一个断点，看到jsonString确实得到了正确的值。但是，我尝试将self.submitView.text设置为任何内容，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＆＃34; task＆＃34;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\":\"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\"}"
这就是我的代码：
do {
let info = try JSONSerialization.jsonObject(with: data, options: .allowFragments) as? [String : Any]
DispatchQueue.main.async {
self.submitView.text = info?["name"] as! String
}
} catch {
DispatchQueue.main.async {
self.submitView.text = "ERROR"
}
}
＆＃34; ERROR＆＃34;不再是打印，而是＆＃34; info＆＃34;似乎有0个键/值对，因此没有打印。
更新：
print(try? JSONSerialization.jsonObject(with: data, options: []))打印＆＃34; nil＆＃34;
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中的文本视图时，这不是什么打印..是否将转义序列转换为文字字符？
答案 0 :(得分：0)
您正在后台线程上设置UITextField的text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执行此操作...
DispatchQueue.main.async {
self.submitView.text = jsonString
}
<强>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。
你可以使用JSON Serialisation class这样做：
// 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中通常会将其转换为字典对象。
有很多可用于Swift的网络资源。我强烈推荐的是iOS Networking with Swift这需要花费相当多的时间来学习，所以这里可以更快地通过Working with JSON in Swift
更新
此代码适用于我：
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)
}