ios线程的常用基本属性 (异步下载图片)

线程的常用基本属性 (异步下载图片)

name : 程序员调试的时候可以使用

优先级 :优先级高的线程不一定比优先级低的线程先执行,完全靠CPU 的算法来

�线程的生命周期

• 新建
• 就绪
• 运行
• 阻塞
• 死亡

实例:

怎么让子线程的图片到主线程来更新界面?

异步下载图片

#import "ViewController.h"

@interface ViewController ()

@property (weak, nonatomic) UIImageView *testImageView;
@property (weak, nonatomic) UIScrollView *scrollView;

@end

@implementation ViewController
//重写此方法,默认不会加载xib&sb
-(void)loadView{
    UIScrollView *sc = [[UIScrollView alloc] initWithFrame:[UIScreen mainScreen].bounds];
    self.scrollView = sc;
    self.view = sc;
    
    UIImageView *imageView = [[UIImageView alloc] init];
    self.testImageView = imageView;
    [self.view addSubview: self.testImageView];
    
    
}

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
//    [self downloadIMG];
    
    //创建线程
    NSThread *thread = [[NSThread alloc] initWithTarget:self selector:@selector(downloadIMG) object:nil];
    [thread start];
}

//下载图片
-(void)downloadIMG{
    NSLog(@"downloadimg %@",[NSThread currentThread]);
    
    //网络卡
//   [NSThread sleepForTimeInterval:3];
    
   
    
    NSString*imgAddr=@"http://jiangsu.china.com.cn/uploadfile/2014/0329/20140329102034577.jpg";
    
    NSURL *url = [NSURL URLWithString:imgAddr];
    //获取到图片的原始数据
    NSData *data = [NSData dataWithContentsOfURL:url];
    UIImage *image = [UIImage imageWithData:data];
    
    //线程间通信 子->主
    //参数1:方法
    //参数2:方法的参数
    //参数3:等待执行完成
    [self performSelectorOnMainThread:@selector(updateUI:) withObject:image waitUntilDone:NO];
    
}

//更新UI
-(void)updateUI:(UIImage *)image{
    NSLog(@"updateUI %@",[NSThread currentThread]);
    self.testImageView.image = image;
    //根据图片的大小来调整位置
    [self.testImageView sizeToFit];
    [self.scrollView setContentSize:image.size];
}
@end