线程与下载

#pragma mark 创建新线程3
- (void)createThread3 {
    // 隐式创建一个新线程执行self的run:方法
    // 创建完毕后马上启动线程
    [self performSelectorInBackground:@selector(run:) withObject:@"mj"];
}

#pragma mark 创建新线程2
- (void)createThread2 {
    // 隐式创建一个新线程执行self的run:方法
    // 创建完毕后马上启动线程
    [NSThread detachNewThreadSelector:@selector(run:) toTarget:self withObject:@"mj"];
}

#pragma mark 创建新线程
- (void)createThread {
    NSThread *thread = [[[NSThread alloc] initWithTarget:self selector:@selector(run:) object:@"mj"] autorelease];
    NSLog(@"thread-%@", thread);
    // 启动线程
    [thread start];
}

#pragma mark 下载图片
- (void)download {
    [self performSelectorInBackground:@selector(downloadImage) withObject:nil];
}

#pragma mark 在后台线程下载图片
- (void)downloadImage {
    NSLog(@"%@", [NSThread currentThread]);
    
    NSString *url = @"http://f.hiphotos.baidu.com/album/w%3D2048/sign=f2f363781e30e924cfa49b3178306f06/9922720e0cf3d7ca8e304106f31fbe096a63a9f8.jpg";
    
    NSURL *URL = [NSURL URLWithString:url];
    NSData *data = [NSData dataWithContentsOfURL:URL];
    UIImage *image = [UIImage imageWithData:data];
    
    // 在主线程调用self.imageView的setImage:方法
    [self.imageView performSelectorOnMainThread:@selector(setImage:) withObject:image waitUntilDone:YES];
}