你文档写的runloop 好像是在主线程执行的runloop

[WoAiLiMoChou]

NSMutableArray mutableIndexPathsToBePrecached = self.fdallIndexPathsToBePrecached.mutableCopy; CFRunLoopObserverRef observer = CFRunLoopObserverCreateWithHandler(kCFAllocatorDefault, kCFRunLoopBeforeWaiting, true, 0, ^(CFRunLoopObserverRef observer, CFRunLoopActivity ) { if (mutableIndexPathsToBePrecached.count == 0) { CFRunLoopRemoveObserver(runLoop, observer, runLoopMode); CFRelease(observer); // 注意释放，否则会造成内存泄露 return; } NSIndexPath indexPath = mutableIndexPathsToBePrecached.firstObject; [mutableIndexPathsToBePrecached removeObject:indexPath]; [self performSelector:@selector(fd_precacheIndexPathIfNeeded:) onThread:[NSThread mainThread] withObject:indexPath waitUntilDone:NO modes:@[NSDefaultRunLoopMode]]; });

:[NSThread mainThread] 这不是主线程执行的runloop吗