Question

我正在尝试在textview中显示输出字符串，但它会将其删除。请检查

NSLog(@"viewcontroller response =%@",responseString); 
txt_output.text=[NSString stringWithFormat:@"%@",strResponse];

txt_output在我的ViewcontrollerB中，我从ViewcontrollerA

返回

NSString *returnstring=[NSString stringWithFormat:@"request=%@ responstring=%@ error=%@",request,responseString,error]; completionHandler(responseString);

在日志上打印Resonse，但在textview上显示后杀死

viewcontroller response =request=<NSMutableURLRequest: 0x786b1b30> { URL: myhosturl } responstring= error=Error Domain=NSURLErrorDomain Code=-1001 "The operation couldn’t be completed. (NSURLErrorDomain error -1001.)" UserInfo=0x786bb400 {NSErrorFailingURLKey=http://myhosturl; NSErrorFailingURLStringKey= myhosturl, NSUnderlyingError=0x7a1790d0 "The operation couldn’t be completed. (kCFErrorDomainCFNetwork error -1001.)"}

Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Only run on the main thread!'
*** First throw call stack:
(
    0   CoreFoundation                      0x01cc5946 __exceptionPreprocess + 182
    1   libobjc.A.dylib                     0x0194ea97 objc_exception_throw + 44
    2   CoreFoundation                      0x01cc57da +[NSException raise:format:arguments:] + 138
    3   Foundation                          0x015c287e -[NSAssertionHandler handleFailureInFunction:file:lineNumber:description:] + 102
    4   UIFoundation                        0x03f2bfc2 -[NSLayoutManager(NSPrivate) _resizeTextViewForTextContainer:] + 418
    5   UIFoundation                        0x03f2bcbe -[NSLayoutManager(NSPrivate) _recalculateUsageForTextContainerAtIndex:] + 2017
    6   UIFoundation                        0x03f659e4 -[NSLayoutManager textStorage:edited:range:changeInLength:invalidatedRange:] + 871
    7   UIFoundation                        0x03f65af4 -[NSLayoutManager processEditingForTextStorage:edited:range:changeInLength:invalidatedRange:] + 85
    8   UIFoundation                        0x03f8f9eb -[NSTextStorage _notifyEdited:range:changeInLength:invalidatedRange:] + 153
    9   UIFoundation                        0x03f8f50a -[NSTextStorage processEditing] + 458
    10  UIFoundation                        0x03f8f094 -[NSTextStorage endEditing] + 80
    11  UIFoundation                        0x03f8f11f -[NSTextStorage coordinateEditing:] + 67
    12  UIKit                               0x00b4631e -[UITextView setAttributedText:] + 250
    13  UIKit                               0x00b4c305 -[UITextView setText:] + 149
    14  MYApp                           0x0003fe75 __36-[TestApiViewController methodcallAPI:]_block_invoke + 197
    15  MYTESTSDK                        0x000d0bb5 __43-[ViewcontrollerA callAPIWithCompletionHandler:]_block_invoke + 533
    16  CFNetwork                           0x02650c03 __49-[__NSCFLocalSessionTask _task_onqueue_didFinish]_block_invoke + 343
    17  Foundation                          0x015eb715 __NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    18  Foundation                          0x01512165 -[NSBlockOperation main] + 99
    19  Foundation                          0x014f1567 -[__NSOperationInternal _start:] + 700
    20  Foundation                          0x014f1299 -[NSOperation start] + 83
    21  Foundation                          0x014f10e3 __NSOQSchedule_f + 237
    22  libdispatch.dylib                   0x02e22e2f _dispatch_client_callout + 14
    23  libdispatch.dylib                   0x02e08afc _dispatch_queue_drain + 1475
    24  libdispatch.dylib                   0x02e083c3 _dispatch_queue_invoke + 212
    25  libdispatch.dylib                   0x02e0b067 _dispatch_root_queue_drain + 466
    26  libdispatch.dylib                   0x02e0c84a _dispatch_worker_thread3 + 115
    27  libsystem_pthread.dylib             0x0317e296 _pthread_wqthread + 724
    28  libsystem_pthread.dylib             0x0317beea start_wqthread + 30
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)

Answer 1

您尝试从主线程以外的线程调用UIKit方法，这是不允许的。这个例外实际上直接告诉你这个＆＃34;原因＆＃34;字段：

Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Only run on the main thread!'

你应该在主线程上运行你的完成块，这样任何UIKit工作块都会在主线程上发生。

Answer 2

您无法在后台线程上执行任何与UI相关的操作。在这里，您尝试在后台线程的textview中设置文本。这就是为什么在主线程上运行异常警报的原因。您可以在主线程上更新textview文本，如下所示。

尝试使用以下代码设置文字：

dispatch_async(dispatch_get_main_queue(), ^{

    NSLog(@"viewcontroller response =%@",responseString);
    txt_output.text=[NSString stringWithFormat:@"%@",strResponse];

});

在UITextview中显示响应时出错

2 个答案: