如果要查找此错误，请使用主线程检查器暂停问题复选框。 在大多数情况下，修复它很容易，只需将有问题的行分派到主队列中即可。

我在使用TouchID时遇到了这个问题，如果这对其他人有帮助，包装你的成功逻辑，它可能在主队列中对UI有作用。

有同样的问题，因为我正在使用performSelectorInBackground。

看看日志里的这一行

$S12AppName18ViewControllerC11Func()ySS_S2StF + 4420

你可以检查哪个函数从后台线程调用，或者你在哪里调用API方法，你需要像这样从主线程调用你的函数。

DispatchQueue.main.async { func()}

Func()是你想在API调用的结果中调用的函数 要么成功，要么失败。

日志在这里

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   Foundation                          0x00000001c570ce50 <redacted> + 96
    1   Foundation                          0x00000001c5501868 <redacted> + 32
    2   Foundation                          0x00000001c5544370 <redacted> + 540
    3   Foundation                          0x00000001c5543840 <redacted> + 396
    4   Foundation                          0x00000001c554358c <redacted> + 272
    5   Foundation                          0x00000001c5542e10 <redacted> + 264
    6   UIKitCore                           0x00000001f20d62e4 <redacted> + 488
    7   UIKitCore                           0x00000001f20d67b0 <redacted> + 36
    8   UIKitCore                           0x00000001f20d6eb0 <redacted> + 84
    9   Foundation                          0x00000001c571d124 <redacted> + 76
    10  Foundation                          0x00000001c54ff30c <redacted> + 108
    11  Foundation                          0x00000001c54fe304 <redacted> + 328
    12  UIKitCore                           0x00000001f151dc0c <redacted> + 156
    13  UIKitCore                           0x00000001f151e0c0 <redacted> + 152
    14  UIKitCore                           0x00000001f1514834 <redacted> + 868
    15  UIKitCore                           0x00000001f1518760 <redacted> + 104
    16  UIKitCore                           0x00000001f1543370 <redacted> + 1772
    17  UIKitCore                           0x00000001f1546598 <redacted> + 120
    18  UIKitCore                           0x00000001f14fc850 <redacted> + 1452
    19  UIKitCore                           0x00000001f168f318 <redacted> + 196
    20  UIKitCore                           0x00000001f168d330 <redacted> + 144
    21  AppName                        0x0000000100b8ed00 $S12AppName18ViewControllerC11Func()ySS_S2StF + 4420
    22  AppName                        0x0000000100b8d9f4 $S12CcfU0_y10Foundation4DataVSg_So13NSURLResponseCSgs5Error_pSgtcfU_ + 2384
    23  App NAme                        0x0000000100a98f3c $S10Foundation4DataVSgSo13NSURLResponseCSgs5Error_pSgIegggg_So6NSDataCSgAGSo7NSErrorCSgIeyByyy_TR + 316
    24  CFNetwork                           0x00000001c513aa00 <redacted> + 32
    25  CFNetwork                           0x00000001c514f1a0 <redacted> + 176
    26  Foundation                          0x00000001c55ed8bc <redacted> + 16
    27  Foundation                          0x00000001c54f5ab8 <redacted> + 72
    28  Foundation                          0x00000001c54f4f8c <redacted> + 740
    29  Foundation                          0x00000001c55ef790 <redacted> + 272
    30  libdispatch.dylib                   0x000000010286f824 _dispatch_call_block_and_release + 24
    31  libdispatch.dylib                   0x0000000102870dc8 _dispatch_client_callout + 16
    32  libdispatch.dylib                   0x00000001028741c4 _dispatch_continuation_pop + 528
    33  libdispatch.dylib                   0x0000000102873604 _dispatch_async_redirect_invoke + 632
    34  libdispatch.dylib                   0x00000001028821dc _dispatch_root_queue_drain + 376
    35  libdispatch.dylib                   0x0000000102882bc8 _dispatch_worker_thread2 + 156
    36  libsystem_pthread.dylib             0x00000001c477917c _pthread_wqthread + 472
    37  libsystem_pthread.dylib             0x00000001c477bcec start_wqthread + 4
)

“这个应用程序正在从后台线程修改自动布局引擎”的主要问题是，它似乎在实际问题发生后很长一段时间才被记录下来，这可能会使它很难排除故障。

我设法通过创建三个符号断点来解决这个问题。

调试>断点>创建符号断点…

断点1:

符号:-[UIView setNeedsLayout] 条件:!(BOOL)[NSThread是主线程]

断点2:

符号:-[UIView layoutIfNeeded] 条件:!(BOOL)[NSThread是主线程]

断点3:

符号:-[UIView updateConstraintsIfNeeded] 条件:!(BOOL)[NSThread是主线程]

使用这些断点，您可以很容易地在非主线程上错误地调用UI方法的实际行中获得断点。

如果要查找此错误，请使用主线程检查器暂停问题复选框。 在大多数情况下，修复它很容易，只需将有问题的行分派到主队列中即可。