GCD-ios 多线程

#import "ViewController.h"@interface ViewController ()@end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];   // [self createMyQueue];        //全局队列   // [self getGlobalQueue];        //主线程    [self getMainQueue];    // Do any additional setup after loading the view, typically from a nib.}#pragma mark -抓取主队列--(void)getMainQueue{    dispatch_async(dispatch_get_main_queue(), ^{        //主线程获取方式        NSLog(@"%@",[NSThread currentThread]);        NSLog(@"isMain:%d",[NSThread isMainThread]);        NSLog(@"isMulti:%d",[NSThread isMultiThreaded]);                [self printFirst];        [self printForth];        [self printSecond];        [self printThird];                        [self printFinish];    });}#pragma mark -GCD的使用-/** *  抓取全局队列 * */-(void)getGlobalQueue{    //获取全局线程    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0);        dispatch_async(queue, ^{        NSLog(@"%@",[NSThread currentThread]);        NSLog(@"isMulti:%d",[NSThread isMultiThreaded]);        [self printFirst];    });        //直接用    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{        NSLog(@"queue2%@",[NSThread currentThread]);        NSLog(@"isMulti2:%d",[NSThread isMultiThreaded]);        [self printSecond];    });        dispatch_async(dispatch_get_global_queue(0, 0), ^{        NSLog(@"queue3%@",[NSThread currentThread]);        NSLog(@"isMulti3:%d",[NSThread isMultiThreaded]);        //3、4 串行        [self printThird];        [self printForth];        [self printFinish];    });        }//1.自己创建//2.系统创建//3.获取主线程//自己创建队列-(void)createMyQueue{    //派遣队列    //参数1：给一个运行标记 参数2：属性：一般传NULL    dispatch_queue_t myQueue= dispatch_queue_create("myQueue", NULL);    //1.同步派遣 串行    dispatch_sync(myQueue, ^{        NSLog(@"%@",[NSThread currentThread]);        NSLog(@"%d",[NSThread isMultiThreaded]);        [self printFirst];    });    dispatch_sync(myQueue, ^{        [self printSecond];    });    dispatch_sync(myQueue, ^{        [self printThird];    });    dispatch_sync(myQueue, ^{        [self printThird];    });        //2.异步演示//    dispatch_async(myQueue, ^{//        //异步创建 新的线程//        NSLog(@"%@",[NSThread currentThread]);//        NSLog(@"%d",[NSThread isMultiThreaded]);//        [self printThird];//        [self printSecond];//        [self printFirst];//    });        //3.创建组    dispatch_group_t group = dispatch_group_create();        dispatch_group_async(group, myQueue, ^{        [self printFirst];    });}#pragma mark -创建几个任务-//打印任务-(void)printFirst{    for (int i = 0 ; i < 10; i++) {        NSLog(@"任务1 执行 %d步",i);        [NSThread sleepForTimeInterval:1.0];    }}-(void)printSecond{    for (int i = 0 ; i < 10; i++) {        NSLog(@"任务2 执行 %d步",i);        [NSThread sleepForTimeInterval:1.0];    }    }-(void)printThird{    for (int i = 0 ; i < 10; i++) {        NSLog(@"任务3 执行 %d步",i);        [NSThread sleepForTimeInterval:1.0];    }    }-(void)printForth{    for (int i = 0 ; i < 10; i++) {        NSLog(@"任务4 执行 %d步",i);        [NSThread sleepForTimeInterval:1.0];    }    }-(void)printFinish{    for (int i = 0 ; i < 10; i++) {        NSLog(@"任务5 执行 %d步",i);        [NSThread sleepForTimeInterval:1.0];    }    }- (void)didReceiveMemoryWarning {    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}@end