iOS 多线程

分手后的思念是犯贱 2022-05-18 10:14 225阅读 0赞

## iOS 多线程开发实现方式: ##

1. NSThread

2. NSOperation

3.GCD

--------------------

### 1.NSThread, 轻量级多线程,需要自己管理声明周期 ###

*  创建线程方法

// 1.Block方法创建 (iOS 10 之后可以使用)
    + (void)detachNewThreadWithBlock:(void (^)(void))block; 
    
    // 2.直接将操作添加到新线程中并执行，该方法无法拿到线程对象
    // @param selector 方法名
    // @param target 调用对象
    // @param argument 参数
    + (void)detachNewThreadSelector:(SEL)selector toTarget:(id)target withObject:(nullable id)argument;
    
    // 3.创建线程对象，初始化线程任务，调用start方法启动线程
    // @param target 调用对象
    // @selector 方法名
    // @param argument 参数
    - (instancetype)initWithTarget:(id)target selector:(SEL)selector object:(nullable id)argument;
    
    
    // eg:
    // 1. block 创建
    [NSThread detachNewThreadWithBlock:^{
        for (int i = 0; i < 100; i ++) {
            KLog(@"%d", i);
        }
    }];
    
    // 2. 直接将操作添加到新线程中并执行
    [NSThread detachNewThreadSelector:@selector(_threadSelector) toTarget:self withObject:nil];
    
    - (void)_threadSelector {
        KLogFunc;
        for (int i = 0; i < 100000; i ++) {
            KLog(@"----------------%d", i);
        }
    }
    
    // 3.创建线程对象，初始化线程任务, 调用start方法启动线程
    NSThread *thread = [[NSThread alloc] initWithTarget:self selector:@selector(_threadSelector) object:nil];
    
    - (void)_threadSelector {
        KLogFunc;
        for (int i = 0; i < 100000; i ++) {
            KLog(@"----------------%d", i);
        }
    }

*  线程操作

// 线程休眠
    + (void)sleepUntilDate:(NSDate *)date;// 让当前线程休眠到某个时间
    + (void)sleepForTimeInterval:(NSTimeInterval)time; // 让当前线程休眠多少秒
    // 终止线程
    + (void)exit;
    // 停止线程, 不会立即停止
    - (void)cancel;

*  线程间通信

// 1.在后台执行一个操作
    - (void)performSelectorInBackground:(SEL)selector withObject:(id)arg;
    
    // 2.在指定的线程执行一个方法,需要创建线程对象
    - (void)performSelector:(SEL)selector onThread:(NSThread *)thread withObject:(id)arg waitUntilDone:(BOOL)wait;
    
    // 3.在主线程执行一个操作
    - (void)performSelectorOnMainThread:(SEL)selector withObject:(id)arg waitUntilDone:(BOOL)wait;
    
    // eg:
    #pragma mark - 添加响应方法触发创建子线程并加载数据
    - (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
    {
        // 创建子线程
        [self performSelectorInBackground:@selector(loadImage) withObject:nil];
    }
    
    - (void)loadImage
    {
    　　 NSLog(@"当前线程：%@", [NSThread currentThread]);  
    　　 NSLog(@"主线程：%@", [NSThread mainThread]);
    
        NSString *urlStr = @"https://ss0.bdstatic.com/94oJfD_bAAcT8t7mm9GUKT-xh_/timg?image&quality=100&size=b4000_4000&sec=1463455875&di=ef2da3f0fe711b471966aa1511483d0b&src=http://img4.duitang.com/uploads/item/201308/20/20130820094450_rsmYi.jpeg";
        
        NSURL *url = [NSURL URLWithString:urlStr];
        
        NSURLRequest *request = [NSURLRequest requestWithURL:url];
        
        self.imageData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
        
        // 返回主线程，刷新UI
        [self performSelectorOnMainThread:@selector(reloadImageView) withObject:nil waitUntilDone:YES];
    }
    
    - (void)reloadImageView
    {
        // 进入主线程一般进行来安全判断
        if ([NSThread isMainThread]) {
            // 刷新UI
            UIImage *showIamge = [UIImage imageWithData:self.imageData];
            
            self.showImageView.image = showIamge;
        }
    }

NSOperation, NSOperationQueue 是苹果提供的一套多线程解决方案,基于GCD封装,完全面向对象

NSOperaion 是对任务的封装,封装好的任务交给NSOperationQueue进行串行队列和并行队列执行.这里的任务就是NSOperation类的一个方法,main方法或start方法,在NSOperation类中这两个方法是空实现,自定义NSOperation时需要重写.OC提供了子类(NSBlockOperation 和 NSInvocationOperation)实现多线程

// 创建NSInvocationOperation
    NSInvocationOperation *operation = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(_operation) object:nil];
    // 创建线程队列
    NSOperationQueue *queue = [[NSOperationQueue alloc] init];
    // 设置最大并发线程数
    queue.maxConcurrentOperationCount = 4;
    // 添加到线程队列后,队列中的线程就会开始执行
    [queue addOperation:operation];
    
    - (void)_operation {
        for (int i = 0; i < 200000; i ++) {
            KLog(@"%d", i);
        }
    }
    
    // 创建NSBlockOperation
    NSBlockOperation *operation = [NSBlockOperation blockOperationWithBlock:^{
        for (int i = 0; i < 1000; i ++) {
            KLog(@"%d", i);
        }
    }];
    [[[NSOperationQueue alloc] init] addOperation:operation];

线程间依赖

// NSOperationQueue 可以控制线程之间的依赖关系.
    - (void)test {
        // 创建线程队列
        NSOperationQueue *operaQueue = [[NSOperationQueue alloc] init];
        // 最大并发数
        operaQueue.maxConcurrentOperationCount = 5;
        NSBlockOperation *lastBlockOperation = [NSBlockOperation         blockOperationWithBlock:^{
            NSLog(@"-----");
        }];
        
        // 创建多个线程
        for (int i = 0; i < 10; i ++) {
            NSBlockOperation *blockOperation = [NSBlockOperation             blockOperationWithBlock:^{
                NSLog(@"-----");
            }];
            // 设置依赖操作
            [blockOperation addDependency:lastBlockOperation];
            [operationQueue addOperation:blockOperation];
        }
        [operationQueue addOperation:lastBlockOperation];
    }

未完结