1.通过代理
在上面的基础上，新建一个类，让其继承自NSOperation。
YYdownLoadOperation.h文件
复制代码//
// YYdownLoadOperation.h
// 01-自定义Operation
//
// Created by apple on 14-6-26.
// Copyright (c) 2014年 itcase. All rights reserved.
//
#import <Foundation/Foundation.h>
#pragma mark-设置代理和代理方法
@class YYdownLoadOperation;
@protocol YYdownLoadOperationDelegate <NSObject>
-(void)downLoadOperation:(YYdownLoadOperation*)operation didFishedDownLoad:(UIImage *)image;
@end
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@interface YYdownLoadOperation : NSOperation
@property(nonatomic,copy)NSString *url;
@property(nonatomic,strong)NSIndexPath *indexPath;
@property(nonatomic,strong)id <YYdownLoadOperationDelegate> delegate;
@end
YYdownLoadOperation.m文件
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//
// YYdownLoadOperation.m
// 01-自定义Operation
//
// Created by apple on 14-6-26.
// Copyright (c) 2014年 itcase. All rights reserved.
//
#import "YYdownLoadOperation.h"
@implementation YYdownLoadOperation
-(void)main
{
NSURL *url=[NSURL URLWithString:self.url];
NSData *data=[NSData dataWithContentsOfURL:url];
UIImage *imgae=[UIImage imageWithData:data];
NSLog(@"--%@--",[NSThread currentThread]);
//图片下载完毕后，通知代理
if ([self.delegate respondsToSelector:@selector(downLoadOperation:didFishedDownLoad:)]) {
dispatch_async(dispatch_get_main_queue(), ^{//回到主线程，传递数据给代理对象
[self.delegate downLoadOperation:self didFishedDownLoad:imgae];
});
}
}
@end
主控制器中的业务逻辑：
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//
// YYViewController.m
// 01-自定义Operation
//
// Created by apple on 14-6-26.
// Copyright (c) 2014年 itcase. All rights reserved.
