info 文件设置网络请求状态为YES

@interface ViewController ()

{

UITextField *tf;

UIButton *btn;

UIImageView *imgView;

}

@end

@implementation ViewController

- (void)viewDidLoad {

[super viewDidLoad];

//btn

btn=[UIButton buttonWithType:UIButtonTypeRoundedRect];

btn.frame=CGRectMake(240, 100, 140, 30);

[btn setTitle:@"获取并显示图片" forState:UIControlStateNormal];

[btn addTarget:self action:@selector(click:) forControlEvents:UIControlEventTouchUpInside];

[self.view addSubview:btn];

//imgView

imgView=[[UIImageView alloc]initWithFrame:CGRectMake(50, 150, 300, 300)];

[self.view addSubview:imgView];

}

-(void)click:(id)sender{

//    sudo apachectl start

NSString *urlStr=@"http://f8.topitme.com/8/5b/d7/11252902191b2d75b8o.jpg";

NSThread *threadA=[[NSThread alloc]initWithTarget:self selector:@selector(downLoadImg:) object:urlStr];

[threadA start];

}

// 下载图片的方法

-(void)downLoadImg:(NSString*)url{

NSURL *uuu = [NSURL URLWithString:url];

NSData *data = [NSData dataWithContentsOfURL:uuu];

NSLog(@"data=%ld",data.length);

UIImage *img=[UIImage imageWithData:data];

// 调用主线程  执行更新图片的功能

if (img!=nil) {

[self performSelectorOnMainThread:@selector(updateImg:) withObject:img waitUntilDone:YES];

}else{

[[[UIAlertView alloc]initWithTitle:@"提示" message:@"图片下载失败" delegate:self cancelButtonTitle:@"OK" otherButtonTitles: nil]show];

}

}

// 更新图片的方法

-(void)updateImg:(UIImage*)img{

imgView.image=img;

}