多线程从入门到放弃

三大常用法宝

本文章着重介绍多线程的基本用法，本文件的例子是下载图片为例子，子线程下载图片，主线程更新图片

经典案例

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    子线程下载任务
    dispatch_async(dispatch_get_main_queue(), ^{
       主线程更新UI
    });
});

NSThread

//动态创建线程
-(void)dynamicCreateThread{
    NSThread *thread = [[NSThread alloc] initWithTarget:self selector:@selector(loadImageSource:) object:imgUrl];
    thread.threadPriority = 1;// 设置线程的优先级(0.0 - 1.0，1.0最高级)
    [thread start];
}

//静态创建线程
-(void)staticCreateThread{
    [NSThread detachNewThreadSelector:@selector(loadImageSource:) toTarget:self withObject:imgUrl];
}

//隐式创建线程
-(void)implicitCreateThread{
    [self performSelectorInBackground:@selector(loadImageSource:) withObject:imgUrl];
}

-(void)loadImageSource:(NSString *)url{
    NSData *imgData = [NSData dataWithContentsOfURL:[NSURL URLWithString:url]];
    UIImage *image = [UIImage imageWithData:imgData];
    if (imgData!=nil) {
        [self performSelectorOnMainThread:@selector(refreshImageView:) withObject:image waitUntilDone:YES];
    }else{
        NSLog(@"there no image data");
    }
}

-(void)refreshImageView:(UIImage *)image{
    [self.loadingLb setHidden:YES];
    [self.imageView setImage:image];
}

NSOperation & NSOperationQueue

//使用子类NSInvocationOperation
-(void)useInvocationOperation{
    NSInvocationOperation *invocationOperation = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(loadImageSource:) object:imgUrl];
    //[invocationOperation start];//直接会在当前线程主线程执行
    NSOperationQueue *queue = [[NSOperationQueue alloc]init];
    [queue addOperation:invocationOperation];
    
}

//使用子类NSBlockOperation
-(void)useBlockOperation{
    
    NSBlockOperation *blockOperation = [NSBlockOperation blockOperationWithBlock:^{
        [self loadImageSource:imgUrl];
    }];
    
    NSOperationQueue *queue = [[NSOperationQueue alloc]init];
    [queue addOperation:blockOperation];
    
}
//使用继承NSOperation
-(void)useSubclassOperation{
    
    LoadImageOperation *imageOperation = [LoadImageOperation new];
    imageOperation.loadDelegate = self;
    imageOperation.imgUrl = imgUrl;
    
    NSOperationQueue *queue = [[NSOperationQueue alloc]init];
    [queue addOperation:imageOperation];
}

-(void)loadImageSource:(NSString *)url{
    
    NSData *imgData = [NSData dataWithContentsOfURL:[NSURL URLWithString:url]];
    UIImage *image = [UIImage imageWithData:imgData];
    if (imgData!=nil) {
        [self performSelectorOnMainThread:@selector(refreshImageView1:) withObject:image waitUntilDone:YES];
    }else{
        NSLog(@"there no image data");
    }
    
}

-(void)refreshImageView1:(UIImage *)image{
    [self.loadingLb setHidden:YES];
    [self.imageView setImage:image];
}

Deme链接：https://github.com/DuffYang/PerfectMutiThread