多线程 GCD

//  DYFViewController.m
//  623-07-GCD
//
//  Created by dyf on 14-6-23.
//  Copyright (c) 2014年 ___FULLUSERNAME___. All rights reserved.
//
 
#import "DYFViewController.h"
 
@interface DYFViewController ()
@property (weak, nonatomic) IBOutlet UIImageView *iconView;
 
@end
 
@implementation DYFViewController
 
- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
     
     
     
     
    /*
    // 异步:具备开启新线程的能力
    dispatch_async(<#dispatch_queue_t queue#>, ^{
        <#code#>
    });
    // 同步:不具备开启新线程的能力
    dispatch_sync(<#dispatch_queue_t queue#>, ^{
        <#code#>
    })
     */
}
 
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    [self testBackToMain];
}
 
- (void)testBackToMain {
    // 获取全局并发队列
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    // 异步队列
    dispatch_async(queue, ^{
        NSLog(@"-----%@", [NSThread currentThread]);
        // 下载图片
        NSString *path = @"http://image.cache.xiu8.com/live/125/125/997729.jpg";
        NSURL *url = [NSURL URLWithString:path];
        NSData *data = [NSData dataWithContentsOfURL:url];
         
        UIImage *image = [UIImage imageWithData:data];
        // 回到主线程显示图片
        dispatch_async(dispatch_get_main_queue(), ^{
            NSLog(@"-----------%@", [NSThread currentThread]);
            self.iconView.image = image;
        });
    });
}
 
- (void)testOnce {
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        NSLog(@"once");
    });
}
 
- (void)testDelay {
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(5.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        NSLog(@"222");
    });
}
 
/**
 *  使用dispatch_async异步函数,在主线程中网主队列中添加任务
 */
- (void)testAsyncMainQueue {
    // 1.获得主队列
    dispatch_queue_t queue = dispatch_get_main_queue();
    // 2.添加任务到队列中,执行任务
    dispatch_async(queue, ^{
        NSLog(@"---------1-----%@", [NSThread currentThread]);
    });
 
    // 总结:不开新线程
     
}
 
/**
 *  使用dispatch_sync同步函数,在主线程中网主队列中添加任务,死:任务无法往下执行
 */
- (void)testSyncMainQueue {
    // 1.获得主队列
    dispatch_queue_t queue = dispatch_get_main_queue();
    // 2.添加任务到队列中,执行任务
    dispatch_sync(queue, ^{
        NSLog(@"---------1-----%@", [NSThread currentThread]);
    });
     
 
    // 总结:不开新线程,所有任务在主线程中串行执行
}
 
// 凡是函数名中带有create、copy、new、retain等字眼,都需要在不需要使用这个数据的时候进行release
// GCD的数据类型在ARC环境下不需要再做release
// CF(Core Foundation)的数据类型在ARC环境下仍然要做release
 
- (void)testCF {
    CFArrayRef array = CFArrayCreate(NULL, NULL, 11, NULL);
    CFRelease(array);
}
 
/**
 *  用dispatch_sync同步函数往串行队列中添加任务
 */
- (void)testSyncSerialQueue {
    // 1.创建串行队列
    dispatch_queue_t queue = dispatch_queue_create("cn.dongyue.queue", NULL);
     
    // 2.添加任务到队列中,执行任务
    dispatch_sync(queue, ^{
        NSLog(@"---------1-----%@", [NSThread currentThread]);
    });
    dispatch_sync(queue, ^{
        NSLog(@"---------2-----%@", [NSThread currentThread]);
    });
    dispatch_sync(queue, ^{
        NSLog(@"---------3-----%@", [NSThread currentThread]);
    });
     
    // 3.释放(MRC)
    //dispatch_release(queue);
     
     
    // 总结:不会开新的线程
}
 
/**
 *  用dispatch_sync同步函数往并发队列中添加任务
 */
- (void)testSyncGlobalQueue {
    // 1.获得全局的并发队列
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
     
    // 2.添加任务到队列中,执行任务
    dispatch_sync(queue, ^{
        NSLog(@"---------1-----%@", [NSThread currentThread]);
    });
    dispatch_sync(queue, ^{
        NSLog(@"---------2-----%@", [NSThread currentThread]);
    });
    dispatch_sync(queue, ^{
        NSLog(@"---------3-----%@", [NSThread currentThread]);
    });
 
    // 总结:不会开启新的线程,并发队列失去了并发功能
}
/**
 *  用dispatch_async同步函数往并发队列中添加任务
 */
- (void)testAsyncSerialQueue {
    // 1.创建串行队列
    dispatch_queue_t queue = dispatch_queue_create("cn.dongyue.queue", NULL);
     
    // 2.添加任务到队列中,执行任务
    dispatch_async(queue, ^{
        NSLog(@"---------1-----%@", [NSThread currentThread]);
    });
    dispatch_async(queue, ^{
        NSLog(@"---------2-----%@", [NSThread currentThread]);
    });
    dispatch_async(queue, ^{
        NSLog(@"---------3-----%@", [NSThread currentThread]);
    });
     
    // 总结:只开1个新的线程,不会开启新的线程
}
/**
 *  用dispatch_async同步函数往并发队列中添加任务
 */
- (void)testAsyncGlobalQueue {
    // 1.获得全局的并发队列
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
     
    // 2.添加任务到队列中,执行任务
    dispatch_async(queue, ^{
        NSLog(@"---------1-----%@", [NSThread currentThread]);
    });
    dispatch_async(queue, ^{
        NSLog(@"---------2-----%@", [NSThread currentThread]);
    });
    dispatch_async(queue, ^{
        NSLog(@"---------3-----%@", [NSThread currentThread]);
    });
    // 总结:同时开启了3个线程
}
 

@end

 
 
posted @ 2015-07-21 12:52  Cheetah_yang  阅读(222)  评论(0编辑  收藏  举报