iOS 开发之 为UIButton添加类别方法加载网络图片

使用GCD线程队列实现

工程如下:

UIButton+WebCache.h

#import <UIKit/UIKit.h>

// 为Button添加类别方法

@interface UIButton (WebCache)

- (void)xr_setButtonImageWithUrl:(NSString *)urlStr;

@end

UIButton+WebCache.m

#import "UIButton+WebCache.h"

@implementation UIButton (WebCache)

- (void)xr_setButtonImageWithUrl:(NSString *)urlStr {

    NSURL * url = [NSURL URLWithString:urlStr];

    // 根据图片的url下载图片数据

    dispatch_queue_t xrQueue = dispatch_queue_create("loadImage", NULL); // 创建GCD线程队列

    dispatch_async(xrQueue, ^{

        // 异步下载图片

        UIImage * img = [UIImage imageWithData:[NSData dataWithContentsOfURL:url]];

        // 主线程刷新UI

        dispatch_async(dispatch_get_main_queue(), ^{

            [self setImage:img forState:UIControlStateNormal];

        });

    });

}

@end

#import <UIKit/UIKit.h>

@interface XRViewController : UIViewController

@property (weak, nonatomic) IBOutlet UIButton *ImgBtn;

@end

#import "XRViewController.h"

#import "UIButton+WebCache.h"

@interface XRViewController ()

@end

@implementation XRViewController

- (void)viewDidLoad

{

    [super viewDidLoad];

// Do any additional setup after loading the view, typically from a nib.

}

- (IBAction)loadImg:(id)sender {

    [self loadImage];

}

- (void)loadImage {

    [_ImgBtn xr_setButtonImageWithUrl:@"http://img3.3lian.com/2014/c2/66/d/56.jpg"];

}

- (void)didReceiveMemoryWarning

{

    [super didReceiveMemoryWarning];

    // Dispose of any resources that can be recreated.

}

@end

效果图:

iOS 开发之 为UIButton添加类别方法加载网络图片