iOS编程------UITableView中图片的异步下载 / KVO监测Model图片下载

//
//  AppDelegate.h
//  UI17_imageDownLoader
//
//  Created by l on 15/9/23.
//  Copyright (c) 2015年 . All rights reserved.
//

#import <UIKit/UIKit.h>

@interface AppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window;

@end

//
//  AppDelegate.m
//  UI17_imageDownLoader
//
//  Created by l on 15/9/23.
//  Copyright (c) 2015年 . All rights reserved.
//

#import "AppDelegate.h"
#import "ImageDownloader.h"
@interface AppDelegate ()<ImageDownloaderDelegate>

@property (nonatomic, retain) UIImageView *imageView;
@end

@implementation AppDelegate
- (void)dealloc{

[_window release];
[_imageView release];
[super dealloc];
}

//实现自定义协议方法
- (void)imageDownloader:(ImageDownloader *)downloader didFinishLoading:(UIImage *)image{

_imageView.image = image;
}

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
// Override point for customization after application launch.
self.window.backgroundColor = [UIColor whiteColor];
[self.window makeKeyAndVisible];

//一. 异步图片下载类
_imageView = [[UIImageView alloc] initWithFrame:(CGRectMake(80, 100, 250, 300))];

//图片同步下载:  (同步网络请求,会卡线程)
//    _imageView.image = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://picm.photophoto.cn/015/037/003/0370032259.jpg"]]];

//--------------//
//代理方法:

[ImageDownloader imageDownloaderWithURLString:@"http://d.hiphotos.baidu.com/image/pic/item/d0c8a786c9177f3ec4c5de0c72cf3bc79f3d5639.jpg" delegate:self];

//-------------//
//block:

//    NSString *url = @"http://img.sootuu.com/vector/2006-4/200642011196982.jpg";
////
//    [ImageDownloader sendAsynchonousURLString:url completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
//
//        //获取到回调的data数据,赋值给imageView.image
//        _imageView.image = [UIImage imageWithData:data];
//    }];
//
//
//加载_imageView
[self.window addSubview:_imageView];

return YES;
}

@end

////////////////////////////////////////////////////////////////////

//
//  ImageDownloader.h
//  UI17_imageDownLoader
//
//  Created by l on 15/9/23.
//  Copyright (c) 2015年 . All rights reserved.
//此为异步图片下载类,封装了系统的connection , 异步网络请求.
//采用delegate 和 block 两种方式.

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>

//定义block类型
typedef void (^CompletionHandler)(NSURLResponse *response, NSData *data, NSError *error);

@class ImageDownloader;

//定义协议
@protocol ImageDownloaderDelegate <NSObject, NSURLConnectionDelegate, NSURLConnectionDataDelegate>

@optional
//图片下载完成之后触发
- (void)imageDownloader:(ImageDownloader *)downloader didFinishLoading:(UIImage *)image;

//图片下载失败的时候触发
- (void)imageDownloader:(ImageDownloader *)downloader didFailWithError:(NSError *)error;

@end

@interface ImageDownloader : NSObject

@property (nonatomic, copy) NSString *urlString;//图片网络地址

//1.delegate
@property (nonatomic, assign) id<ImageDownloaderDelegate> delegate;

//自定义初始化方法
- (instancetype)initWithURLString:(NSString *)urlString delegate:(id<ImageDownloaderDelegate>) delegate;
//便利构造器
+ (ImageDownloader *)imageDownloaderWithURLString:(NSString *)urlString delegate:(id<ImageDownloaderDelegate>) delegate;

+ (void)sendAsynchonousURLString:(NSString *)urlString completionHandler:(CompletionHandler)handler;

@end

//
//  ImageDownloader.m
//  UI17_imageDownLoader
//
//  Created by l on 15/9/23.
//  Copyright (c) 2015年 . All rights reserved.
//

#import "ImageDownloader.h"
@interface ImageDownloader ()<NSURLConnectionDelegate, NSURLConnectionDataDelegate>
@property (nonatomic, retain) NSMutableData *receiveData;

@end

@implementation ImageDownloader
- (void)dealloc{

[_urlString release];
[_receiveData release];
[super dealloc];
}

//重写初始化方法(自定义初始化方法)
- (instancetype)initWithURLString:(NSString *)urlString delegate:(id<ImageDownloaderDelegate>) delegate{

self = [super init];
if (self) {
self.urlString = urlString;
self.delegate = delegate;

//进行网络请求
NSURL *url = [NSURL URLWithString:_urlString];

NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:url cachePolicy:0 timeoutInterval:10];

//异步网络请求方式,代理
[NSURLConnection connectionWithRequest:request delegate:self];

}
return self;
}

//便利构造器
+ (ImageDownloader *)imageDownloaderWithURLString:(NSString *)urlString delegate:(id<ImageDownloaderDelegate>) delegate{

return [[[ImageDownloader alloc] initWithURLString:urlString delegate:delegate] autorelease];
}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{

self.receiveData = [NSMutableData data];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{

[self.receiveData appendData:data];
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection{

//数据接收完成后,把数据通过协议的方法,作为方法参数,传递给delegate

UIImage *image = [UIImage imageWithData:self.receiveData];

if (_delegate != nil && [_delegate respondsToSelector:@selector(imageDownloader:didFinishLoading:)]) {

[_delegate imageDownloader:self didFinishLoading:image];
}
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{

if (_delegate != nil && [_delegate respondsToSelector:@selector(imageDownloader:didFailWithError:)]) {

[_delegate imageDownloader:self didFailWithError:error];
}
}

//block
+ (void)sendAsynchonousURLString:(NSString *)urlString completionHandler:(CompletionHandler)handler{

NSURL *url = [NSURL URLWithString:urlString];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
[NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {

//把参数通过block的参数传递出去
handler(response, data, connectionError);
}];
}

@end