UI-多线程

iOS多线程详解

最新推荐文章于 2024-04-05 21:06:53 发布

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最新推荐文章于 2024-04-05 21:06:53 发布

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文章标签： ui c# 数据库

原文链接：http://www.cnblogs.com/devZhou/p/4872701.html

一丶多线程概述

一个应用程序就是一个进程; (包含多个子线程) 一个进程包括多个线程 ;

线程与线程之间可以共享进程的内存区域

iOS中关于UI的添加必须在主线程中操作 .

二丶NSThread

轻量级多线程,两种创建方法实例化需要手动开启子线程类方法初始化的时候已经开启;

注意: 在多线程方法中需要添加到自动释放池 2,在应用程序打开的时候,系统会自动为主线程创建一个自动释放池,而我们手动创建子线程,

//创建子线程
-(void)createThread
{
    NSLog(@"..........");
    NSThread *thread = [[NSThread alloc]initWithTarget:self selector:@selector(btnAction) object:nil];
    [thread start];
    [thread release];

}

//类方法

[NSThread detachNewThreadSelector:@selector(btnAction) toTarget:self withObject:nil];

三丶NSOperation(基类 )

只能继承,用它的子类

//创建nsoperation线程
-(void)createOperation
{
    NSInvocationOperation *invacation = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(btnAction) object:nil];
    [invacation start];
    [invacation release];

}

NSOperationQueue 线程并发

    NSInvocationOperation *invacation = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(btnAction) object:nil];
//    [invacation start];
//    [invacation release];
    NSInvocationOperation *invacation1 = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(btnAction) object:nil];
    NSInvocationOperation *invacation2 = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(btnAction) object:nil];
    NSOperationQueue *queue = [[NSOperationQueue alloc]init];
    [queue addOperation:invacation];
    [queue addOperation:invacation1];
    [queue addOperation:invacation2];
    [queue setMaxConcurrentOperationCount:3]; //最大并发数
    [invacation release];
    [invacation1 release];
    [invacation2 release];
    [queue release];

} 先放进去,先执行并发的时候,现执行前面的

NSObject 中存了一个最简单的后台执行方法

//后台执行某个方法 //系统自动给创建一个子线程，执行任务完成后自动回收

与NSThread 类创建区别手动创建,指定方法
-(void)createObject
{
//系统爱怎么做就怎么做
[self performSelectorInBackground:@selector(btnAction) withObject:nil];

}

返回主线程方法

GCD: dispatch_get_main_queue()

NSObject: [self performSelectorOnMainThread:@selector(updateUI:) withObject:image waitUntilDone:YES];

下载完成后用performSelectorOnMainThread执行主线程updateUI方法。

两个线程之间进行通信:

[self performSelector:@selector(mainAction:) onThread:[NSThread mainThread] withObject:[NSNumber numberWithInt:sum] waitUntilDone:YES];

//GCD 返回主线程
-(void)backMainThread:(id)sender
{
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        __block int sum = 0;
        for (int i = 0; i < 10000; i++) {
            sum += i;
        }
        dispatch_async(dispatch_get_main_queue(), ^{
            NSLog(@"sum ======%d",sum);
        });

    });

}

四丶GCD

先进先执行,后进后执行.

GCD中三种队列:

dispatch queue分为下面三种:

1.Serial:只执行一个任务,Serial queue通常用于同步访问特定的资源或者数据,当你创建多个时,各自同步执行,但Serial queue之间是并发执行的

  //1 获取系统的串行队列,就是主线程的
    //顺序执行
    dispatch_queue_t serialQueue = dispatch_get_main_queue();
    dispatch_async(serialQueue, ^{
        NSLog(@"第1个任务,所在线程是%@,是否是主线程%d",[NSThread currentThread],[[NSThread currentThread]isMainThread]);// (线程,是否主线程)

    });
    dispatch_async(serialQueue, ^{
        NSLog(@"第2个任务,所在线程是%@,是否是主线程%d",[NSThread currentThread],[[NSThread currentThread]isMainThread]);// (线程,是否主线程)

    });
    dispatch_async(serialQueue, ^{
        NSLog(@"第3个任务,所在线程是%@,是否是主线程%d",[NSThread currentThread],[[NSThread currentThread]isMainThread]);// (线程,是否主线程)

    });

}

2.Concurrent: 可以并发执行多个任务,但是执行完的顺序是随机的

//创建并行线程队列
-(void)concurrentButton:(id)sender
{
//1,获取系统的dispatch_global_queue
dispatch_queue_t globalQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0); //(线程优先级.共4种), (要预留参数)

//先执行Block块里的功能
    dispatch_async(globalQueue, ^{
        NSLog(@"第一个任务,所在线程是%@,是否是主线程%d",[NSThread currentThread],[[NSThread currentThread]isMainThread]);// (线程,是否主线程)
    });
    dispatch_async(globalQueue, ^{
        NSLog(@"第二个任务,所在线程是%@,是否是主线程%d",[NSThread currentThread],[[NSThread currentThread]isMainThread]);// (线程,是否主线程)
    });
    dispatch_async(globalQueue, ^{
        NSLog(@"第三个任务,所在线程是%@,是否是主线程%d",[NSThread currentThread],[[NSThread currentThread]isMainThread]);// (线程,是否主线程)
    });

      //2,自己创建并行队列
    dispatch_queue_t myConcurrentQueue = dispatch_queue_create("lanou", DISPATCH_QUEUE_CONCURRENT);//(C#不可变字符串线程队列名字,串行或者并行)
    dispatch_async(myConcurrentQueue, ^{
        NSLog(@"计算结果:");
        [self action1];

任务

    });

}

3.Main dispatch queue:全局可用,它使应用程序主线上执行任务的