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iOS多线程之NSThread的使用

iOS多线程之NSThread的使用

作者: iOS心安 | 来源:发表于2020-12-03 14:55 被阅读0次

    NSThread是多线程的一种，优缺点如下：

    （1）优点：NSThread 比GCD、NSOperation都轻量级

    （2）缺点：需要自己管理线程的生命周期，线程同步。线程同步对数据的加锁会有一定的系统开销
    NSThread有两种方法创建子线程，一种是隐式创建，另一种是显示创建。

    第一种是隐式创建，有以下几种方式：

    （1）多用于串行，且在主线程中执行。

    - (id)performSelector:(SEL)aSelector withObject:(id)object;

    （2）后台执行，多用于并行，开辟新的子线程，并在子线程中执行。

    - (void)performSelectorInBackground:(SEL)aSelector withObject:(nullable id)arg;

    （3）延迟执行，在主线程中执行。

    - (void)performSelector:(SEL)aSelector withObject:(nullable id)anArgument afterDelay:(NSTimeInterval)delay;

    （4）回到主线程执行

    - (void)performSelectorOnMainThread:(SEL)aSelector withObject:(nullable id)arg waitUntilDone:(BOOL)wait;

    停止执行的方法

    + (void)cancelPreviousPerformRequestsWithTarget:(id)aTarget selector:(SEL)aSelector object:(nullable id)anArgument;

    + (void)cancelPreviousPerformRequestsWithTarget:(id)aTarget

    示例：创建子线程-隐式方法

    // 串行，先后顺序执行，在主线程中执行
- (void)runSerial
{
    [self performSelector:@selector(showTime:) withObject:@11];
    [self performSelector:@selector(showTime:) withObject:@12];
    [self performSelector:@selector(showTime:) withObject:@13];
}
 
- (void)showTime:(id)object
{
        NSLog(@"主线程：%d, 线程名称：%@, object = %@", [NSThread isMainThread], [NSThread currentThread], object);
}
 
2018-03-06 14:35:46.010 DemoThread[6369:1254531] 主线程：1, 线程名称：<NSThread: 0x600000077d40>{number = 1, name = main}, object = 11
2018-03-06 14:35:46.011 DemoThread[6369:1254531] 主线程：1, 线程名称：<NSThread: 0x600000077d40>{number = 1, name = main}, object = 12
2018-03-06 14:35:46.011 DemoThread[6369:1254531] 主线程：1, 线程名称：<NSThread: 0x600000077d40>{number = 1, name = main}, object = 13

    // 并行，同时进行，执行结果没有午后顺序，开辟新的子线程，并在子线程中执行
- (void)runParallel
{
    [self performSelectorInBackground:@selector(showTime:) withObject:@110];
    [self performSelectorInBackground:@selector(showTime:) withObject:@120];
    [self performSelectorInBackground:@selector(showTime:) withObject:@130];
}
 
- (void)showTime:(id)object
{    
        NSLog(@"主线程：%d, 线程名称：%@, object = %@", [NSThread isMainThread], [NSThread currentThread], object);
}
 
2018-03-06 14:37:04.270 DemoThread[6392:1256565] 主线程：0, 线程名称：<NSThread: 0x600000074ac0>{number = 11, name = (null)}, object = 130
2018-03-06 14:37:04.270 DemoThread[6392:1256563] 主线程：0, 线程名称：<NSThread: 0x60000006d000>{number = 9, name = (null)}, object = 110
2018-03-06 14:37:04.270 DemoThread[6392:1256564] 主线程：0, 线程名称：<NSThread: 0x60000007acc0>{number = 10, name = (null)}, object = 120

    // 延迟执行，在主线程中执行
- (void)runDelay
{
    [self performSelector:@selector(showTime:) withObject:@210 afterDelay:1.0];
    [self performSelector:@selector(showTime:) withObject:@220 afterDelay:2.0];
    [self performSelector:@selector(showTime:) withObject:@230 afterDelay:3.0];
}
 
- (void)showTime:(id)object
{    
        NSLog(@"主线程：%d, 线程名称：%@, object = %@", [NSThread isMainThread], [NSThread currentThread], object);
}
 
// 根据打印时间，可以看出延迟执行时间
2018-03-06 14:38:03.808 DemoThread[6420:1257666] 主线程：1, 线程名称：<NSThread: 0x60000007e640>{number = 1, name = main}, object = 210
2018-03-06 14:38:04.809 DemoThread[6420:1257666] 主线程：1, 线程名称：<NSThread: 0x60000007e640>{number = 1, name = main}, object = 220
2018-03-06 14:38:05.809 DemoThread[6420:1257666] 主线程：1, 线程名称：<NSThread: 0x60000007e640>{number = 1, name = main}, object = 230

    // 在主线程中执行，waitUntilDone为NO时，表示非阻塞当前线程，即先执行完当前线程，再执行showTime:方法
- (void)runMain
{
    NSLog(@"begin");
    [self performSelectorOnMainThread:@selector(showTime:) withObject:@310 waitUntilDone:NO];
    [self performSelectorOnMainThread:@selector(showTime:) withObject:@320 waitUntilDone:NO];
    [self performSelectorOnMainThread:@selector(showTime:) withObject:@330 waitUntilDone:NO];
    NSLog(@"end");
}
 
- (void)showTime:(id)object
{    
        NSLog(@"主线程：%d, 线程名称：%@, object = %@", [NSThread isMainThread], [NSThread currentThread], object);
}
 
2018-03-06 14:40:04.668 DemoThread[6463:1260294] begin
2018-03-06 14:40:04.668 DemoThread[6463:1260294] end
2018-03-06 14:40:04.669 DemoThread[6463:1260294] 主线程：1, 线程名称：<NSThread: 0x608000067440>{number = 1, name = main}, object = 310
2018-03-06 14:40:04.669 DemoThread[6463:1260294] 主线程：1, 线程名称：<NSThread: 0x608000067440>{number = 1, name = main}, object = 320
2018-03-06 14:40:04.669 DemoThread[6463:1260294] 主线程：1, 线程名称：<NSThread: 0x608000067440>{number = 1, name = main}, object = 330

    // 在主线程中执行，waitUntilDone为YES时，表示阻塞当前线程，即先执行完showTime:方法，再执行当前线程
- (void)runMain
{
    NSLog(@"begin");
    [self performSelectorOnMainThread:@selector(showTime:) withObject:@310 waitUntilDone:YES];
    [self performSelectorOnMainThread:@selector(showTime:) withObject:@320 waitUntilDone:YES];
    [self performSelectorOnMainThread:@selector(showTime:) withObject:@330 waitUntilDone:YES];
    NSLog(@"end");
}
 
- (void)showTime:(id)object
{    
        NSLog(@"主线程：%d, 线程名称：%@, object = %@", [NSThread isMainThread], [NSThread currentThread], object);
}
 
2018-03-06 14:44:05.614 DemoThread[6495:1264100] begin
2018-03-06 14:44:05.614 DemoThread[6495:1264100] 主线程：1, 线程名称：<NSThread: 0x608000064a40>{number = 1, name = main}, object = 310
2018-03-06 14:44:05.615 DemoThread[6495:1264100] 主线程：1, 线程名称：<NSThread: 0x608000064a40>{number = 1, name = main}, object = 320
2018-03-06 14:44:05.615 DemoThread[6495:1264100] 主线程：1, 线程名称：<NSThread: 0x608000064a40>{number = 1, name = main}, object = 330
2018-03-06 14:44:05.615 DemoThread[6495:1264100] end
    第二种是显示创建，方式如下：
    + (void)detachNewThreadSelector:(SEL)selector toTarget:(id)target withObject:(nullable id)argument;

    + (void)detachNewThreadWithBlock:(void (^)(void))block;

    - (instancetype)initWithTarget:(id)target selector:(SEL)selector object:(nullable id)argument;

    注意：
    （1）通过方法" - (void)start; "开始执行；
    （2）通过方法" - (void)cancel; "停止执行；

    示例：创建子线程-显示方法

    // 并行，同时进行，执行结果没有先后顺序，开辟新的子线程，并在子线程中执行
- (void)runDetach
{
    [NSThread detachNewThreadSelector:@selector(showTime:) toTarget:self withObject:@410];
    [NSThread detachNewThreadSelector:@selector(showTime:) toTarget:self withObject:@420];
    [NSThread detachNewThreadSelector:@selector(showTime:) toTarget:self withObject:@430];
    
    [NSThread detachNewThreadWithBlock:^{
        [self showTime:@4100];
    }];
}
 
- (void)showTime:(id)object
{    
        NSLog(@"主线程：%d, 线程名称：%@, object = %@", [NSThread isMainThread], [NSThread currentThread], object);
}
 
2018-03-06 14:47:23.918 DemoThread[6535:1268056] 主线程：0, 线程名称：<NSThread: 0x6080000773c0>{number = 13, name = (null)}, object = 430
2018-03-06 14:47:23.918 DemoThread[6535:1268054] 主线程：0, 线程名称：<NSThread: 0x608000063940>{number = 11, name = (null)}, object = 410
2018-03-06 14:47:23.919 DemoThread[6535:1268055] 主线程：0, 线程名称：<NSThread: 0x60800007da80>{number = 12, name = (null)}, object = 420
2018-03-06 14:47:23.919 DemoThread[6535:1268057] 主线程：0, 线程名称：<NSThread: 0x60000007bd80>{number = 14, name = (null)}, object = 4100

    self.thread = [[NSThread alloc] initWithTarget:self selector:@selector(showCount:) object:@(61)];
 self.thread.name = @"计数";
 [self.thread start];
 [self.thread cancel];

    代码示例

    - (void)showCount:(NSNumber *)number
{
    NSInteger count = arc4random() % 1000;
    count = 1000;
    for (int i = 0; i < count; i++)
    {
        NSLog(@"第 %@ 个 i = %@", number, @(i));
        
        // 休眠n秒再执行
        [NSThread sleepForTimeInterval:0.2];
        
        // 停止
//        BOOL isStop = [self.thread isCancelled];
//        if (isStop)
//        {
//            NSLog(@"2 停止");
//            break;
//        }
        if (isCancelThread)
        {
            NSLog(@"2 停止");
            break;
        }
    }
}

    bool isCancelThread = NO;
- (void)stopClick
{
    [NSObject cancelPreviousPerformRequestsWithTarget:self];
    
    if (self.thread)
    {
        BOOL isExecuting = [self.thread isExecuting];
        if (isExecuting)
        {
            NSLog(@"1 停止");
//            [self.thread cancel];
            isCancelThread = YES;
        }
    }
}

    
- (void)downloadImage:(NSString *)imageUrl
{
    NSURL *url = [NSURL URLWithString:imageUrl];
    NSData *data = [[NSData alloc] initWithContentsOfURL:url];
    UIImage *image = [[UIImage alloc] initWithData:data];
    if (image == nil)
    {
        
    }
    else
    {
//        [self performSelectorOnMainThread:@selector(updateImage:) withObject:image waitUntilDone:YES];
        [self performSelectorInBackground:@selector(updateImage:) withObject:image];
    }
    
//    NSURL *url = [NSURL URLWithString:imageUrl];
//    NSURLRequest *request = [NSURLRequest requestWithURL:url];
//    NSURLSession *session = [NSURLSession sharedSession];
//    NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:request completionHandler: ^(NSData *data, NSURLResponse *response, NSError *error) {
//        
//        // 输出返回的状态码，请求成功的话为200
//        NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *)response;
//        NSInteger responseStatusCode = [httpResponse statusCode];
//        NSLog(@"%ld", responseStatusCode);
//        
//        UIImage *image = [UIImage imageWithData:data];
        [self performSelectorOnMainThread:@selector(updateImage:) withObject:image waitUntilDone:YES];
//        [self performSelectorInBackground:@selector(updateImage:) withObject:image];
//    }];
//    
//    // 使用resume方法启动任务
//    [dataTask resume];
}

    - (void)updateImage:(UIImage *)image
{
    self.imageview.image = image;
    
//    self.imageview = [[UIImageView alloc] initWithFrame:CGRectMake(10.0, 10.0, (CGRectGetWidth(self.view.bounds) - 10.0 * 2), (CGRectGetWidth(self.view.bounds) - 10.0 * 2))];
//    [self.view addSubview:self.imageview];
//    self.imageview.backgroundColor = [UIColor colorWithWhite:0.5 alpha:0.2];
//    
//    self.imageview.image = image;
}

    
NSString *imageUrl = @"http://ww1.sinaimg.cn/crop.0.0.1242.1242.1024/763fb12bjw8empveq3eq8j20yi0yiwhw.jpg";
// 隐藏创建
// [self performSelectorInBackground:@selector(downloadImage:) withObject:imageUrl];
[self performSelectorOnMainThread:@selector(downloadImage:) withObject:imageUrl waitUntilDone:YES];
// 创建子线程-显示方法
self.thread = [[NSThread alloc] initWithTarget:self selector:@selector(downloadImage:) object:imageUrl];
self.thread.name = @"imageDownload";
[self.thread start];

    其他

    // 线程信息
NSLog(@"%@", [NSThread currentThread]);
 
2018-03-06 14:19:02.575 DemoThread[6214:1238492] <NSThread: 0x600000072bc0>{number = 1, name = main}

    // 线程大小 512 KB
NSLog(@"主线程栈区空间大小 => %tu", [NSThread currentThread].stackSize / 1024);
 
2018-03-06 14:19:02.575 DemoThread[6214:1238492] 主线程栈区空间大小 => 512

    // 是否主线程
NSLog(@"主线程：%d, ", [NSThread isMainThread]);
 
2018-03-06 14:19:02.576 DemoThread[6214:1238663] 主线程：0

    本文来自 番薯大佬

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