.h
#import <UIKit/UIKit.h>
@protocol imageDownloadDelegate <NSObject>
@optional
-(void)imageDownloadWithImage:(UIImage *)image;
@end
// 声明一个block 参数类型是UIImage 返回值是void 别名Result
typedef void(^Result)(UIImage *img);
@interface ImageDownload : NSObject
#pragma mark - 声明方法 被调用后直接下载
+(void)imageDownloadWithUrlStr:(NSString *)urlStr
delegate:(id<imageDownloadDelegate>)delegate;
#pragma mark - 声明方法 使用block的方式
+(void)imageDownloadWithUrlStr:(NSString *)urlStr
result:(Result)result;
@end
#import "ImageDownload.h"
@implementation ImageDownload
#pragma mark - 实现方法 代理
+(void)imageDownloadWithUrlStr:(NSString *)urlStr
delegate:(id<imageDownloadDelegate>)delegate
{
NSURL *url = [NSURL URLWithString:urlStr];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
[NSURLConnection sendAsynchronousRequest:request queue:[[NSOperationQueue new]autorelease] completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
UIImage *image = [UIImage imageWithData:data];
dispatch_sync(dispatch_get_main_queue(),^{
if (delegate!=nil && [delegate respondsToSelector:@selector(imageDownloadWithImage:)]) {
[delegate imageDownloadWithImage:image];
}
});
}];
}
#pragma mark - 实现方法 block 方式
+(void)imageDownloadWithUrlStr:(NSString *)urlStr
result:(Result)result
{
NSURL *url = [NSURL URLWithString:urlStr];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
[NSURLConnection sendAsynchronousRequest:request queue:[[NSOperationQueue new]autorelease] completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
UIImage *image = [UIImage imageWithData:data];
// 回到主线程使用block
dispatch_sync(dispatch_get_main_queue(), ^{
// block 调用
result(image);
});
}];
}
再去 ViewController
- (IBAction)buttonAction:(UIButton *)sender
{
/*
//
//1 NSURL
NSURL *url = [NSURL URLWithString:@""];
//2 NSURLREQUEST
NSURLRequest *request = [NSURLRequest requestWithURL:url];
//3 NSURLConnection
__block ViewController *weakSelf = self;
[NSURLConnection sendAsynchronousRequest:request queue:[[NSOperationQueue new]autorelease] completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
//4 获取data数据 转为UIImage类型
UIImage *image = [UIImage imageWithData:data];
//5 回到主界面 刷新数据
dispatch_sync(dispatch_get_main_queue(),^{
weakSelf.imageView.image = image;
});
}];
*/
// 直接发送消息 设置代理
// [ImageDownload imageDownloadWithUrlStr:@"" delegate:self];
// 使用block
__block ViewController *weakSelf = self;
[ImageDownload imageDownloadWithUrlStr:@"http://img4.duitang.com/uploads/item/201208/10/20120810091225_hvA2r.thumb.700_0.jpeg" result:^(UIImage *img)
{
// 将block中参数显示到UIImageView上
weakSelf.imageView.image = img;
}];
}
@end