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案例多图下载
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
[self blockOperation];
}
- (void)blockOperation
{
NSBlockOperation *op = [NSBlockOperation blockOperationWithBlock:^{
// 在主线程
NSLog(@"下载1------%@", [NSThread currentThread]);
}];
// 添加额外的任务(在子线程执行)
[op addExecutionBlock:^{
NSLog(@"下载2------%@", [NSThread currentThread]);
}];
[op addExecutionBlock:^{
NSLog(@"下载3------%@", [NSThread currentThread]);
}];
[op addExecutionBlock:^{
NSLog(@"下载4------%@", [NSThread currentThread]);
}];
[op start];
}
NSInvocationOperation
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NSBlockOperation
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NSOperationQueue
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最大并发数
Paste_Image.png
队列的取消\恢复\暂停
Paste_Image.png
操作依赖
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操作监听
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自定义NSOperation
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自定义NSOperation图片下载思路--沙盒缓存
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自定义NSOperation图片下载思路--无沙盒缓存
Paste_Image.png
多图下载合成新图
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
__block UIImage *image1 = nil;
// 下载图片1
NSBlockOperation *download1 = [NSBlockOperation blockOperationWithBlock:^{
// 图片的网络路径
NSURL *url = [NSURL URLWithString:@"http://img.pconline.com.cn/images/photoblog/9/9/8/1/9981681/200910/11/1255259355826.jpg"];
// 加载图片
NSData *data = [NSData dataWithContentsOfURL:url];
// 生成图片
image1 = [UIImage imageWithData:data];
}];
__block UIImage *image2 = nil;
// 下载图片2
NSBlockOperation *download2 = [NSBlockOperation blockOperationWithBlock:^{
// 图片的网络路径
NSURL *url = [NSURL URLWithString:@"http://pic38.nipic.com/20140228/5571398_215900721128_2.jpg"];
// 加载图片
NSData *data = [NSData dataWithContentsOfURL:url];
// 生成图片
image2 = [UIImage imageWithData:data];
}];
// 合成图片
NSBlockOperation *combine = [NSBlockOperation blockOperationWithBlock:^{
// 开启新的图形上下文
UIGraphicsBeginImageContext(CGSizeMake(100, 100));
// 绘制图片
[image1 drawInRect:CGRectMake(0, 0, 50, 100)];
image1 = nil;
[image2 drawInRect:CGRectMake(50, 0, 50, 100)];
image2 = nil;
// 取得上下文中的图片
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
// 结束上下文
UIGraphicsEndImageContext();
// 回到主线程
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
self.imageView.image = image;
}];
}];
[combine addDependency:download1];
[combine addDependency:download2];
[queue addOperation:download1];
[queue addOperation:download2];
[queue addOperation:combine];
}
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