__NSFastEnumerationMutationHandler

xcode 获取的崩溃日志中有一篇日志信息如下

image.png

查看代码videoDrawViewWillHide方法中时一个数组遍历的方法,查询相关资料后差不多可以确定是在遍历数组的过程中修改或者删除了数组的元素导致, 编写demo 重现问题

  removeArr = [[NSMutableArray alloc] initWithCapacity:1];
    
    for (int i = 0; i < 100; i++) {
        [removeArr addObject:[NSString stringWithFormat:@"%d", I]];
    }
    
    dispatch_async(dispatch_queue_create("ergodicArr", DISPATCH_QUEUE_SERIAL), ^{
        [self ergodicArr];
    });
    
    dispatch_async(dispatch_queue_create("removaArr", DISPATCH_QUEUE_SERIAL), ^{
        [self removeArry];
    });

-(void)removeArry{
    for (int i = 20; i < 30; i++) {
        [self->removeArr removeObject:[NSString stringWithFormat:@"%d",I]];
    }
    NSLog(@"removearr = %@", self->removeArr);
}

-(void)ergodicArr
{
    for (NSString *obj in removeArr) {
        [NSThread sleepForTimeInterval:0.1];
        NSLog(@"obj = %@", obj);
    }
}

编译运行结果如下

image.png

得到了与崩溃日志中相同的结果
解决方案:修改遍历方法

 dispatch_async(dispatch_queue_create("ergodicArr", DISPATCH_QUEUE_SERIAL), ^{
        [self ergodicArr1];
    });

-(void)ergodicArr1
{
    [removeArr enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
        [NSThread sleepForTimeInterval:0.1];
        NSLog(@"obj = %@", obj);
    }];
}

编译运行 正常