NSThread

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//线程创建方法1 -- allo + init
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- (void)createThread1 {
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    /*
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    第一个参数：目标对象 self
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    第二个参数：方法选择器 -> 调用的方法
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    第三个参数：前面调用的方法需要传递的参数 -> nil
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    */
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    NSThread *thread = [[NSThread alloc] initWithTarget:self
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      selector:@selector(run:)
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        object:@"test"];
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    //启动线程
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    [thread start];
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    //设置线程属性
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    thread.name = @"线程A";
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    [thread setName:@"线程A"];
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    //设置线程优先级 -- 优先级大小(0.0 ~ 1.0), 默认为0.5
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    thread.threadPriority = 1.0;
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    //线程生命周期 -- 当任务执行完成之后被释放
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}
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//线程创建方法2 -- 无法获取创建的线程对象
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- (void)createThread2 {
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    //分离子线程方法
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    [NSThread detachNewThreadSelector:@selector(run:) toTarget:self withObject:@"通过分离子线程创建新线程"];
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}
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//线程创建方法3-- 无法获取创建的线程对象
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- (void)createThread3 {
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    //开启后台线程方法
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    [self performSelectorInBackground:@selector(run:) withObject:@"通过开启后台线程创建新线程"];
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}
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- (void)test:(NSString *)para {
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    NSLog(@"-----test-----%@", [NSThread currentThread]);
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}

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- (void)createThread1 {
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    //新建状态
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    NSThread *thread = [[NSThread alloc] initWithTarget:self selector:@selector(run:) object:@"test"];
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  //就绪或运行状态
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    [thread start];
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}
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- (void)test:(NSString *)para {
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    NSLog(@"-----test-----%@", [NSThread currentThread]);
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    //阻塞状态
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    [NSThread sleepFortimeinterval:2.0];
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    [NSThread sleepUntilDate:[NSDate dateWithTimeIntervalSinceNow:3.0]];
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  //死亡状态
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    [NSThread exit];
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}

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//网络图片下载Demo -- NSThread实现
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#import "ViewController.h"
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@interface ViewController ()
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@property(nonatomic, strong) UIImageView *imageView;
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@property(nonatomic, strong) NSThread *threadA;
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@end
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@implementation ViewController
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//耗时操作要用子线程进行
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- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
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    //分离一条子线程去执行download方法
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    [NSThread detachNewThreadSelector:@selector(download) toTarget:self withObject:nil];
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}
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- (void)download {
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    //确定图片URL
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    NSURL *url = [NSURL URLWithString:@"https://gimg2.baidu.com/image_search/src=http%3A%2F%2Fa1.att.hudong.com%2F62%2F02%2F01300542526392139955025309984.jpg&refer=http%3A%2F%2Fa1.att.hudong.com&app=2002&size=f9999,10000&q=a80&n=0&g=0n&fmt=jpeg?sec=1613890070&t=9b041b83f4ddfe8c165547120f5aa589"];
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    //根据URL下载图片二进制数据到本地
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    NSData *imageData = [NSData dataWithContentsOfURL:url];
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    //图片格式转换
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    UIImage *image = [UIImage imageWithData:imageData];
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    //回到主线程显示UI的三种方法
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    //方法1
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    /*
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     参数1：回到主线程要调用的方法
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     参数2：前面方法需要的参数
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     参数3：当前方法剩余部分的执行是否等待参数1方法执行完毕
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     */
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    [self performSelectorOnMainThread:@selector(showImage:) withObject:image waitUntilDone:YES];
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    //方法2 -- 主动选择执行线程为主线程
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    [self performSelector:@selector(showImage:) onThread:[NSThread mainThread] withObject:image waitUntilDone:YES];
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    //方法3 -- 直接用self.imageView调用主线程方法
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    [self.imageView performSelectorOnMainThread:@selector(setImage:) withObject:image waitUntilDone:YES];
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}
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- (void)showImage:(UIImage *)image {
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    self.imageView.image = image;
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}
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@end