ios之多线程-NSThead、GCD、NSOperationQueue

1.NSthead使用：

 创建方式1：

NSThread *thead  = [[NSThread alloc]initWithTarget:self selector:@selector(run:) object:@"第一种"];    thead.name = @"one";//线程名称    [thead start];//开启线程

  创建方式2：

   [NSThread detachNewThreadSelector:@selector(run:) toTarget:self withObject:@"第二种"]; 

  创建方式3：

 [self performSelectorInBackground:@selector(run:) withObject:@"第三种"];

  run方法：

-(void)run:(NSThread *)sender{    NSLog(@"--%@---%@",sender.observationInfo,[NSThread currentThread]);    for (int i=0; i<100000; i++) {        if(self.thead.isCancelled){//调用cancel方法设置为yes             NSLog(@"NShread exit:%d",i);            [NSThread exit];//类方法 只能在线程里面运行在主线程运行会阻挡主线程代码的运行        }else        NSLog(@"NShread:%d",i);    }}

关闭NSThead线程：

[thead cancel];//此方法设置thead.isCancelled为yes，所以可在线程里面执行thead.isCancelled来做相对应处理方法

2.NSOperationQueue使用

-(void)queueOperation{    NSOperationQueue *queue = [[NSOperationQueue alloc]init];//创建线程    NSInvocationOperation *op1 = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(download) object:nil];//任务1    NSBlockOperation *op2 = [NSBlockOperation blockOperationWithBlock:^{        NSLog(@"downLoad2--%@",[NSThread currentThread]);    }];//任务2    [op2 addExecutionBlock:^{        NSLog(@"downLoad3--%@",[NSThread currentThread]);    }];    CustomNSOperation *op3 = [[CustomNSOperation alloc]init];//任务三    [queue addOperation:op1];//自动掉用start    [queue addOperation:op2];    [queue addOperation:op3];}

CustomNSOperation类CustomNSOperation类继承NSOperation，在.m文件里面调用main方法。如下例子：

#import <Foundation/Foundation.h>@interface CustomNSOperation : NSOperation //.h@end

#import "CustomNSOperation.h"//.m@implementation CustomNSOperation-(void)main{    NSLog(@"自定义---%@",[NSThread currentThread]);}@end

3. CGD使用最常用的有6中方法：（如下）

// !!!: 同步+主队列-(void)syncMain{    dispatch_queue_t queue = dispatch_get_main_queue();    NSLog(@"sync ---begin");    //将任务加入队列    dispatch_sync(queue, ^{        NSLog(@"1---%@",[NSThread currentThread]);    });    dispatch_sync(queue, ^{        NSLog(@"2---%@",[NSThread currentThread]);    });    dispatch_sync(queue, ^{        NSLog(@"3---%@",[NSThread currentThread]);    });    NSLog(@"sync ---end");}// TODO:异步+主队列-(void)asynMain{    dispatch_queue_t queue = dispatch_get_main_queue();     NSLog(@"async( ---begin");    dispatch_async(queue, ^{         NSLog(@"1---%@",[NSThread currentThread]);    });    dispatch_async(queue, ^{        NSLog(@"2---%@",[NSThread currentThread]);    });    dispatch_async(queue, ^{        NSLog(@"3---%@",[NSThread currentThread]);    });    NSLog(@"async( ---end");}// FIXME:同步+串行队列：不会开启新的线程，在当前线程执行任务-(void)syncSerial{    dispatch_queue_t queue = dispatch_queue_create("com.520.queue", DISPATCH_QUEUE_SERIAL);    //创建串行队列    dispatch_sync(queue, ^{        NSLog(@"sync Serial---begin");        //将任务加入队列        dispatch_sync(queue, ^{            NSLog(@"1---%@",[NSThread currentThread]);        });        dispatch_sync(queue, ^{            NSLog(@"2---%@",[NSThread currentThread]);        });        dispatch_sync(queue, ^{            NSLog(@"3---%@",[NSThread currentThread]);        });        NSLog(@"sync ---end");        NSLog(@"sync Serial---end");    });}// ???:异步+串行队列:会开启新的线程，但是任务是串行的，执行一个任务，在执行下一个任务-(void)asyncSerial{    dispatch_queue_t queue = dispatch_queue_create("com.520.queue", DISPATCH_QUEUE_SERIAL);    NSLog(@"async(Serial ---begin");    dispatch_async(queue, ^{        NSLog(@"1---%@",[NSThread currentThread]);    });    dispatch_async(queue, ^{        NSLog(@"2---%@",[NSThread currentThread]);    });    dispatch_async(queue, ^{        NSLog(@"3---%@",[NSThread currentThread]);    });    NSLog(@"async( Serial---end");}// !!!:同步+并发队列 不会开启线程-(void)syncConcurrent{     //获取全局的并发队列    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);    NSLog(@"async(Concurrent ---begin");    dispatch_async(queue, ^{        NSLog(@"1 Concurrent---%@",[NSThread currentThread]);    });    dispatch_async(queue, ^{        NSLog(@"2 Concurrent---%@",[NSThread currentThread]);    });    dispatch_async(queue, ^{        NSLog(@"3 Concurrent---%@",[NSThread currentThread]);    });    NSLog(@"async( Concurrent---end");}// !!!:异步+并发队列 可以同时开启多条线程-(void)asycConcurrent{    //创建一个队列    //第一个参数是标签等同于名字    //第二个参数传串行还是并行    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);    //将任务添加到队列    dispatch_async(queue, ^{        for (int i=0; i<10000; i++) {          NSLog(@"1 Concurrent---%@",[NSThread currentThread]);        }    });    dispatch_async(queue, ^{        for (int i=0; i<100000; i++) {            NSLog(@"2 Concurrent---%@",[NSThread currentThread]);        }    });    dispatch_async(queue, ^{        for (int i=0; i<100000; i++) {            NSLog(@"3 Concurrent---%@",[NSThread currentThread]);        }    });}

以上是ios三种线程使用方式，当线程运行后如何调用刷新主线程UI。调用此方法：[self performSelectorOnMainThread: withObject: waitUntilDone:];//刷新主线程
例子：
以NSthead为列：

-(void)createThead1{    self.thead = [[NSThread alloc]initWithTarget:self selector:@selector(run:) object:@"第一种"];    self.thead.name = @"one";    [self.thead start];}-(void)run:(NSThread *)sender{    NSLog(@"--%@---%@",sender.observationInfo,[NSThread currentThread]);    for (int i=0; i<100000; i++) {        if(self.thead.isCancelled){             NSLog(@"NShread exit:%d",i);             [self performSelectorOnMainThread:@selector(updateUI:) withObject:nil waitUntilDone:YES];//刷新主线程            [NSThread exit];//类方法        }else        NSLog(@"NShread:%d",i);    }}-(void)updateUI:(NSThread *)sender{    NSLog(@"刷新主线程UI");}- (IBAction)btnThead1:(id)sender {   [self.thead cancel];}

当btnThead1:这个方法时，设置了self.thead.isCancelled=YES，在线程里面就运行self.thead.isCancelled里面的方法。注意：只有当线程里面的任务完成才能运行dealloc()方法。

4.  三种线程的优缺点

NSThread:
优点：NSThread 比其他两个轻量级
缺点：需要自己管理线程的生命周期，线程同步。线程同步对数据的加锁会有一定的系统开销。
NSOperation
优点：不需要关心线程管理，数据同步的事情，可以把精力放在自己需要执行的操作上。
NSOperationQueue
operation 相关的类是 NSOperation ，
NSOperation是个抽象类，使用它必须用它的子类，可以实现它或者使用它定义好的两个子类：NSInvocationOperation 和 NSBlockOperation。
创建NSOperation子类的对象，把对象添加到NSOperationQueue队列里执行。
GCD
Grand Central Dispatch (GCD)是Apple开发的一个多核编程的解决方法。在iOS4.0开始之后才能使用。GCD是一个替代诸如NSThread, NSOperationQueue, NSInvocationOperation等技术的很高效和强大的技术。现在的iOS系统都升级到7了，所以不用担心该技术不能使用