MultiThreadObject *object = [[MultiThreadObject alloc] init];
NSLock *lock = [[NSLock alloc] init];
[NSThread detachNewThreadWithBlock:^{
    NSInteger loopCount = 1000;
    while (loopCount) {
        [lock lock];
        NSArray *data = @[@"1", @"2", @"3"];
        object.data = data;
        if (object.data != data) {
            NSLog(@"多线程同步问题 self.data: %@, data: %@",object.data, data);
        }
        loopCount --;
        [lock unlock];
    }
}];
[NSThread detachNewThreadWithBlock:^{
    NSInteger loopCount = 1000;
    while (loopCount) {
        [lock lock];
        NSArray *data = @[@"1", @"2", @"3", @"4"];
        object.data = data;
        loopCount --;
        [lock unlock];
    }
}];