IOS加载网络图片的框架（共有4中方法）

框架名为：UIImage+WebCache.h   继承于UIimageView

框架里面加载网络图片的方法共4中：分别为1.普通加载   2.线程NSThread    3.

#import "ViewController.h"

#import "UIImage+WebCache.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {

    [super viewDidLoad];

    imageArray = [NSMutableArray array];

    for(int i = 0;i < 5;i++){

        for(int j = 0;j < 6;j++){

            UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(j*65 +5, i*64 +10, 60, 60)];

            imageView.backgroundColor = [UIColor cyanColor];

            [self.view addSubview:imageView];

            [imageArray addObject:imageView];

        }

    }

    UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];

    button.frame = CGRectMake(160, 400, 80, 30);

    [button setTitle:@"载入" forState:UIControlStateNormal];

    [button addTarget:self action:@selector(buttonAction) forControlEvents:UIControlEventTouchUpInside];

    [self.view addSubview:button];

}

- (void)buttonAction{

    for(UIImageView *imageView in imageArray){

       NSString *string = @"http://img3.douban.com/view/photo/photo/public/p2221339563.jpg";

        NSURL *url = [NSURL URLWithString:string];

        [imageView setImageWithURL:url];

    }

}

#import <UIKit/UIKit.h>

@interface UIImageView (WebCache)

- (void)setImageWithURL:(NSURL *)url;

@end

#import "UIImage+WebCache.h"

@implementation UIImageView (WebCache)

- (void)setImageWithURL:(NSURL *)url{

    //第一种方法：普通的加载

    /*

    NSData *data = [NSData dataWithContentsOfURL:url];

    UIImage *image = [UIImage imageWithData:data];

    [self setImage:image];

    */

    //第二种方法：线程

    //NSThread *thread = [[NSThread alloc] initWithTarget:self selector:@selector(loadImage:) object:url];

    //[thread start];

    //第三种方法：队列

  /*  NSOperationQueue *queue = [[NSOperationQueue alloc] init];

    //操作数

    NSBlockOperation *op = [NSBlockOperation blockOperationWithBlock:^{

        NSData *data = [NSData dataWithContentsOfURL:url];

        UIImage *image = [UIImage imageWithData:data];

        //使用主队列来回到主线程

        //在主线程上修改UI

        [[NSOperationQueue mainQueue] addOperationWithBlock:^{

            //修改UI界面

        [self setImage:image];

        }];

    }];

    [queue addOperation:op];

    */

    //----------------GCD---------------

//    //1.创建Queue

//    dispatch_queue_t queue = dispatch_queue_create("com.xw.gcd.queue", DISPATCH_QUEUE_CONCURRENT);//并行队列

//    

//    //2.创建要执行的任务，加到队列中

//    dispatch_async(queue, ^{

//        

//        NSData *data = [NSData dataWithContentsOfURL:url];

//        UIImage *image = [UIImage imageWithData:data];

//        [self setImage:image];

//    });

    //用系统给的queue---

    //  (两个参数)

    //参数1：优先级

    //参数2：标识符

    dispatch_queue_t globalQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);

    dispatch_async(globalQueue, ^{

    //请求数据

        NSData *data = [NSData dataWithContentsOfURL:url];

        UIImage *image = [UIImage imageWithData:data];

        //显示在UI界面上

        dispatch_async(dispatch_get_main_queue(), ^{

            //UI相关的代码

            //UI界面的刷新最好回到主线程中

            [self setImage:image];

        });

    });

}

- (void)loadImage:(NSURL *)url{

    NSData *data = [NSData dataWithContentsOfURL:url];

    UIImage *image = [UIImage imageWithData:data];

    [self setImage:image];

}

@end