iOS--线程间通讯NSThread--04

最新推荐文章于 2024-07-27 00:00:04 发布

刘海阳

最新推荐文章于 2024-07-27 00:00:04 发布

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文章标签：线程线程通讯 NSThread

本文链接：https://blog.youkuaiyun.com/liuhaiyanga/article/details/52442057

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本文介绍了一种iOS应用中图片的异步加载方法。通过在后台线程下载图片，并使用performSelectorOnMainThread方法将图片更新到ImageView上，确保了UI线程的流畅运行。这种方法可以有效避免因网络请求造成的UI卡顿。

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1.回到主线程，刷新UI界面(为了线程安全)

#import "HMViewController.h"

@interface HMViewController ()
@property (weak, nonatomic) IBOutlet UIImageView *imageView;
@end

@implementation HMViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    [self performSelectorInBackground:@selector(download) withObject:nil];
}

/**
 *  下载图片
 */
- (void)download
{
    NSLog(@"download---%@", [NSThread currentThread]);
    // 1.图片地址
    NSString *urlStr = @"http://d.hiphotos.baidu.com/image/pic/item/37d3d539b6003af3290eaf5d362ac65c1038b652.jpg";
    NSURL *url = [NSURL URLWithString:urlStr];

    // 2.根据地址下载图片的二进制数据(这句代码最耗时)
    NSLog(@"---begin");
    NSData *data = [NSData dataWithContentsOfURL:url];
    NSLog(@"---end");

    // 3.设置图片
    UIImage *image = [UIImage imageWithData:data];

    // 4.回到主线程，刷新UI界面(为了线程安全)
    [self performSelectorOnMainThread:@selector(downloadFinished:) withObject:image waitUntilDone:NO];
//    [self performSelector:@selector(downloadFinished:) onThread:[NSThread mainThread] withObject:image waitUntilDone:YES];
//    [self.imageView performSelectorOnMainThread:@selector(setImage:) withObject:image waitUntilDone:YES];

    NSLog(@"-----done----");
}

- (void)downloadFinished:(UIImage *)image
{
    self.imageView.image = image;

    NSLog(@"downloadFinished---%@", [NSThread currentThread]);
}