AFNetworking简单使用起来进行下载图片

继ASIHTTPRequest发布不再维护的消息之后，如果我们不使用CDN(云服务器)，AFNetworking会是一套不错的选择 。

下載網址：https://github.com/AFNetworking/AFNetworking
下载之后，直接进入Xcode的工程即可以用，记得加入SystemConfiguration.framework
范例参考：

在application: didFinishLaunchingWithOptions： 加入AFNetworkActivityIndicatorManager

记得
#import "AFNetworkActivityIndicatorManager.h"

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
[[AFNetworkActivityIndicatorManager sharedManager] setEnabled:YES];
self.window.backgroundColor = [UIColor whiteColor];

[self.window makeKeyAndVisible];
return YES;
}

这是我们常用的下载网路资源（JSON 格式）

记得

#import "AFHTTPClient.h"

#import "AFHTTPRequestOperation.h"

#import "JSONKit.h"

NSURL *url = [NSURL URLWithString:@"http://www.domain.com"];
AFHTTPClient *httpClient = [[AFHTTPClient alloc] initWithBaseURL:url];
NSString *_path=[NSString stringWithFormat:@"/user_login/%@/%@/",userName,password];
NSMutableURLRequest *request = [httpClient requestWithMethod:@"POST" path:_path parameters:nil];
[httpClient release];

AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];

[operation  setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
//下载成功之后，使用JSONKit将字串转成NSDictionary或NSArray 格式
NSDictionary *deserializedData = [operation.responseString objectFromJSONString];

}
failure:^(AFHTTPRequestOperation *operation, NSError *error) {
//下载失败的处理    }];

NSOperationQueue *queue = [[[NSOperationQueue alloc] init] autorelease];
[queue addOperation:operation];

我们做完上一个步骤，有時候会得到一些图片的绝对地址，接下來就是根据这些URL地址，进行异步下载图片。

记得 #import "UIImageView+AFNetworking.h"

简单的做法是

[imageView setImageWithURL:@"图片的绝对路径"];

复杂的做法，可以在图片下载完成之后，再去触发一些事件

NSURL *url = [NSURL URLWithString:@图片的绝对路径"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:30.0];
[imageView setImageWithURLRequest:request placeholderImage:nil
success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image) {
NSLog(@"图片下载成功！do something");
} failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error) {
NSLog(@图片下载成功！do something"");
}];""