iOS 未销毁常见原因整理

1 强引用 timer

• fix: 未调用invalidate 且 置为 nil

2 页面退出时 perform after 仍未执行

• eg: [self performSelector:@selector(sel) withObject:nil afterDelay:30];
• fix: [NSObject cancelPreviousPerformRequestsWithTarget:self];

3 页面退出时 dispatch after 仍未执行

• eg: dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 50), dispatch_get_main_queue(), ^{})
• fix: __weak typeof(self) weakSelf = self;

    __weak typeof(self) weakSelf = self;
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        __strong typeof(self) self = weakSelf;
//        [self actionTimer:100];
    });