iOS 下载图片

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//

//  下载图片

//  Created by 石虎 on 17/6/18.

//  Copyright © 2017年
石虎. All rights reserved.

//

#import "ViewController.h"

/**

注意:1.只需要把以下代码拷贝到项目就可以用

     2.如果需要换图片,把宏定义的URL地址换了即可

*/

//创建图片地址

#define URL  @"https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1497842327410&di=ac2a6e0a6bd2dcc7330f234393a4ea8e&imgtype=0&src=http%3A%2F%2Fscimg.jb51.net%2Fallimg%2F160106%2F14-160106152915B2.jpg"

@interface
ViewController ()

//显示的图片

@property (strong,
nonatomic) UIImageView *imageView;

//点击下载图片按钮

@property (strong,
nonatomic) UIButton *downloadBtn;

@end

@implementation ViewController

- (void)viewDidLoad

{

    [super
viewDidLoad];

    

    //1.创建图片控件

    _imageView =[[UIImageView alloc]initWithFrame:CGRectMake(30,
20, self.view.frame.size.width-60,
450)];

    //图片背景颜色

    _imageView.backgroundColor=[UIColor lightGrayColor];

    //把图片添加到视图 View
上面

    [self.view addSubview:_imageView];

    

    //2.创建下载图片按钮

    _downloadBtn=[[UIButton alloc]initWithFrame:CGRectMake(100,
500, 120,
30)];

   
//按钮上面添加文字

    [_downloadBtn setTitle:@"点击下载图片" forState:UIControlStateNormal];

    //字体颜色

    [_downloadBtn setTitleColor:[UIColor redColor] forState:UIControlStateNormal];

    //字体背景

    _downloadBtn.backgroundColor=[UIColor lightGrayColor];

    //按钮点击事件

    [_downloadBtn addTarget:self action:@selector(imageClick) forControlEvents:UIControlEventTouchUpInside];

    [self.view addSubview:_downloadBtn];

}

-(void)imageClick

{

    NSLog(@"--->>图片按钮被点击了！！！");

    _downloadBtn.backgroundColor=[UIColor redColor];

    

    [_downloadBtn setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];

    //根据字符串生成url对象

    NSURL *url=[NSURL URLWithString:URL];

    //创建多线程

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

    //开启线程

    [thread start];

    

}

-(void)downLodImage:(NSURL*)url

{

   
//根据url获取图片的二进制数据

    NSData *data=[NSData dataWithContentsOfURL:url];

    UIImage *imageView2=[UIImage imageWithData:data];

    [self performSelectorOnMainThread:@selector(imageRefresh:) withObject:imageView2 waitUntilDone:NO];

}

//刷新主线程

-(void)imageRefresh:(UIImage*)image

{

    //全局图片

    _imageView.image=image;

}

@end