UI related task processing on Background thread

[zishanj]

I am receiving this in error log when using asynchronous = YES

Main Thread Checker: UI API called on a background thread: -[UIView bounds]
PID: 7206, TID: 258580, Thread name: (none), Queue name: NSOperationQueue 0x60000022e280 (QOS: UNSPECIFIED), QoS: 0
Backtrace:
4   FXImageView                         0x00000001074dab67 -[FXImageView cacheKey] + 215
5   FXImageView                         0x00000001074db1f4 -[FXImageView processImage] + 52
6   FXImageView                         0x00000001074d9e7f -[FXImageOperation main] + 63
7   Foundation                          0x0000000109b51cd6 -[__NSOperationInternal _start:] + 778
8   libdispatch.dylib                   0x000000010d37043c _dispatch_client_callout + 8
9   libdispatch.dylib                   0x000000010d375af4 _dispatch_block_invoke_direct + 592
10  libdispatch.dylib                   0x000000010d37043c _dispatch_client_callout + 8
11  libdispatch.dylib                   0x000000010d375af4 _dispatch_block_invoke_direct + 592
12  libdispatch.dylib                   0x000000010d375884 dispatch_block_perform + 109
13  Foundation                          0x0000000109b4dce4 __NSOQSchedule_f + 342
14  libdispatch.dylib                   0x000000010d37043c _dispatch_client_callout + 8
15  libdispatch.dylib                   0x000000010d376856 _dispatch_continuation_pop + 967
16  libdispatch.dylib                   0x000000010d374c86 _dispatch_async_redirect_invoke + 780
17  libdispatch.dylib                   0x000000010d37c1f9 _dispatch_root_queue_drain + 772
18  libdispatch.dylib                   0x000000010d37be97 _dispatch_worker_thread3 + 132
19  libsystem_pthread.dylib             0x000000010d82c5a2 _pthread_wqthread + 1299
20  libsystem_pthread.dylib             0x000000010d82c07d start_wqthread + 13
2017-10-11 14:50:12.061475+0500 Asma-ul-Husna[7206:258580] [reports] Main Thread Checker: UI API called on a background thread: -[UIView bounds]
PID: 7206, TID: 258580, Thread name: (none), Queue name: NSOperationQueue 0x60000022e280 (QOS: UNSPECIFIED), QoS: 0
Backtrace:
4   FXImageView                         0x00000001074dab67 -[FXImageView cacheKey] + 215
5   FXImageView                         0x00000001074db1f4 -[FXImageView processImage] + 52
6   FXImageView                         0x00000001074d9e7f -[FXImageOperation main] + 63
7   Foundation                          0x0000000109b51cd6 -[__NSOperationInternal _start:] + 778
8   libdispatch.dylib                   0x000000010d37043c _dispatch_client_callout + 8
9   libdispatch.dylib                   0x000000010d375af4 _dispatch_block_invoke_direct + 592
10  libdispatch.dylib                   0x000000010d37043c _dispatch_client_callout + 8
11  libdispatch.dylib                   0x000000010d375af4 _dispatch_block_invoke_direct + 592
12  libdispatch.dylib                   0x000000010d375884 dispatch_block_perform + 109
13  Foundation                          0x0000000109b4dce4 __NSOQSchedule_f + 342
14  libdispatch.dylib                   0x000000010d37043c _dispatch_client_callout + 8
15  libdispatch.dylib                   0x000000010d376856 _dispatch_continuation_pop + 967
16  libdispatch.dylib                   0x000000010d374c86 _dispatch_async_redirect_invoke + 780
17  libdispatch.dylib                   0x000000010d37c1f9 _dispatch_root_queue_drain + 772
18  libdispatch.dylib                   0x000000010d37be97 _dispatch_worker_thread3 + 132
19  libsystem_pthread.dylib             0x000000010d82c5a2 _pthread_wqthread + 1299
20  libsystem_pthread.dylib             0x000000010d82c07d start_wqthread + 13

Although the images renders well but need to get rid from these thread related errors.

[pnovales]

You should try:

- (NSString *)cacheKey
{
    if (_cacheKey) return _cacheKey;
    
    __block NSString* s;
    
    dispatch_block_t block = ^{
        s = [NSString stringWithFormat:@"%@_%@_%.2f_%.2f_%.2f_%@_%@_%.2f_%.2f_%@",
                       _imageContentURL ?: [self imageHash:_originalImage],
                       NSStringFromCGSize(self.bounds.size),
                       _reflectionGap,
                       _reflectionScale,
                       _reflectionAlpha,
                       [self colorHash:_shadowColor],
                       NSStringFromCGSize(_shadowOffset),
                       _shadowBlur,
                       _cornerRadius,
                       @(self.contentMode)];
    };

    if ([NSThread currentThread].isMainThread) {
        block();
    } else {
        dispatch_sync(dispatch_get_main_queue(), block);
    }
    
    return s;
}

For more info:
https://developer.apple.com/documentation/code_diagnostics/main_thread_checker