iOS-多线程--介绍NSThread和GCD及其它们的线程通讯示例
前言：下面就不一一列出 pthread、NSThread、GCD、NSOperation 的完整的各种方法了，只分别将最常用的列出来，以便偶尔瞄一眼。
一、NSThread
1> 线程间的通讯
/** 这个例子为在创建的子线程中下载图片，然后回到主线程中设置图片 ( 更新UI ) */
- (void)viewDidLoad
{
[super viewDidLoad];
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
// 隐式创建并启动线程
[self performSelectorInBackground:@selector(download) withObject:nil];
}
/**
* 图片下载
*/
- (void)download
{
NSLog(@"download---%@", [NSThread currentThread]);
// 1.图片地址
NSString *urlStr = @"http://d.hiphotos.baidu.com/image/pic/item/37d3d539b6003af3290eaf5d362ac65c1038b652.jpg";
NSURL *url = [NSURL URLWithString:urlStr];
// 2.根据地址下载图片的二进制数据(耗时的代码)
NSLog(@"---begin");
NSData *data = [NSData dataWithContentsOfURL:url];
NSLog(@"---end");
// 3.设置图片
UIImage *image = [UIImage imageWithData:data];
// 4.回到主线程，刷新UI界面(为了线程安全)
[self performSelectorOnMainThread:@selector(downloadFinished:) withObject:image waitUntilDone:NO];
// [self performSelector:@selector(downloadFinished:) onThread:[NSThread mainThread] withObject:image waitUntilDone:YES];
// [self.imageView performSelectorOnMainThread:@selector(setImage:) withObject:image waitUntilDone:YES];
NSLog(@"-----over----");
}
- (void)downloadFinished:(UIImage *)image
{
self.imageView.image = image;
NSLog(@"downloadFinished---%@", [NSThread currentThread]);
}
@end
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二、GCD
1> 、GCD 【 (任务)同步/异步***(队列)串行/并发*****任务和队列的几种组合方式 】
- (void)viewDidLoad
{
[super viewDidLoad];
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
[self asyncSerialQueue];
}
// 就下面三个最常用，(GCD中其他情况不要管)
/**
* 第一种组合方式
* async -- 并发队列（最常用）
* 会不会创建线程：会，一般同时开多条
* 任务的执行方式：并发执行
*/
- (void)asyncGlobalQueue
{
// 获得全局的并发队列
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
// 将 任务 添加 全局队列 中去 异步 执行
dispatch_async(queue, ^{
NSLog(@"-----下载图片1---%@", [NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"-----下载图片2---%@", [NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"-----下载图片3---%@", [NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"-----下载图片4---%@", [NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"-----下载图片5---%@", [NSThread currentThread]);
});
}
/**
*第一种组合方式 打印结果
2016-04-07 17:48:05.007 Test-GCD测试一下[909:50754] -----下载图片2---<NSThread: 0x7f8acb50ea50>{number = 3, name = (null)}
2016-04-07 17:48:05.007 Test-GCD测试一下[909:50755] -----下载图片1---<NSThread: 0x7f8acb4bedf0>{number = 2, name = (null)}
2016-04-07 17:48:05.007 Test-GCD测试一下[909:50762] -----下载图片4---<NSThread: 0x7f8acb71b570>{number = 5, name = (null)}
2016-04-07 17:48:05.007 Test-GCD测试一下[909:50763] -----下载图片5---<NSThread: 0x7f8acb510160>{number = 6, name = (null)}
2016-04-07 17:48:05.007 Test-GCD测试一下[909:50758] -----下载图片3---<NSThread: 0x7f8acb60e780>{number = 4, name = (null)}
*/
/**
* 第二种组合方式
* async -- 串行队列（有时候用）
* 会不会创建线程：会，一般只开1条线程
* 任务的执行方式：串行执行（一个任务执行完毕后再执行下一个任务）
*/
- (void)asyncSerialQueue
{
// 1.创建一个串行队列
dispatch_queue_t queue = dispatch_queue_create("cn.heima.queue", NULL);
// 2.将任务添加到串行队列中 异步 执行
dispatch_async(queue, ^{
NSLog(@"-----下载图片1---%@", [NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"-----下载图片2---%@", [NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"-----下载图片3---%@", [NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"-----下载图片4---%@", [NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"-----下载图片5---%@", [NSThread currentThread]);
});
// 3.非ARC，需要释放创建的队列
// dispatch_release(queue);
}
/**
* 第二种方式 打印结果
2016-04-07 17:49:33.730 Test-GCD测试一下[921:52233] -----下载图片1---<NSThread: 0x7f926ad09e20>{number = 2, name = (null)}
2016-04-07 17:49:33.731 Test-GCD测试一下[921:52233] -----下载图片2---<NSThread: 0x7f926ad09e20>{number = 2, name = (null)}
2016-04-07 17:49:33.731 Test-GCD测试一下[921:52233] -----下载图片3---<NSThread: 0x7f926ad09e20>{number = 2, name = (null)}
2016-04-07 17:49:33.731 Test-GCD测试一下[921:52233] -----下载图片4---<NSThread: 0x7f926ad09e20>{number = 2, name = (null)}
2016-04-07 17:49:33.731 Test-GCD测试一下[921:52233] -----下载图片5---<NSThread: 0x7f926ad09e20>{number = 2, name = (null)}
*/
/**
* 第三种方式 （这是一种特殊的方式，将 任务 添加到主队列中 异步 执行）
* async -- 主队列(很常用) （一般在线程之间的通讯才用得上 @xz）
*/
- (void)asyncMainQueue
{
// 1.主队列(添加到主队列中的任务，都会自动放到主线程中去执行)
dispatch_queue_t queue = dispatch_get_main_queue();
// 2.添加 任务 到主队列中 异步 执行
dispatch_async(queue, ^{
NSLog(@"-----下载图片1---%@", [NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"-----下载图片2---%@", [NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"-----下载图片3---%@", [NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"-----下载图片4---%@", [NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"-----下载图片5---%@", [NSThread currentThread]);
});
}
/**
* 第三种方式 打印结果如下：
2016-04-07 16:50:04.245 Test-GCD测试一下[801:31778] -----下载图片1---<NSThread: 0x7fb2a2d0a1e0>{number = 1, name = main}
2016-04-07 16:50:04.246 Test-GCD测试一下[801:31778] -----下载图片2---<NSThread: 0x7fb2a2d0a1e0>{number = 1, name = main}
2016-04-07 16:50:04.246 Test-GCD测试一下[801:31778] -----下载图片3---<NSThread: 0x7fb2a2d0a1e0>{number = 1, name = main}
2016-04-07 16:50:04.247 Test-GCD测试一下[801:31778] -----下载图片4---<NSThread: 0x7fb2a2d0a1e0>{number = 1, name = main}
2016-04-07 16:50:04.248 Test-GCD测试一下[801:31778] -----下载图片5---<NSThread: 0x7fb2a2d0a1e0>{number = 1, name = main}
*/
2> GCD------线程间通讯示例
注意点：
<1>. 需要设置按钮的image和backgroundImage，建议先把按钮类型改为custom，才能保证设置成功
<2>. 属性名不能以new开头
<3>. 只有在init开头的构造方法中，才允许对self进行赋值
#define XZGlobalQueue dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)
#define XZMainQueue dispatch_get_main_queue()
#import "XZViewController.h"
@interface XZViewController ()
@property (weak, nonatomic) IBOutlet UIButton *button;
@end
@implementation XZViewController
- (void)viewDidLoad
{
[super viewDidLoad];
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UIButton *button = [[UIButton alloc] initWithFrame:CGRectMake(20, 20, 100, 60)];
[self.view addSubview:button];
self.button = button;
dispatch_async(XZGlobalQueue, ^{
NSLog(@"donwload---%@", [NSThread currentThread]);
// 1.子线程下载图片
NSURL *url = [NSURL URLWithString:@"http://d.hiphotos.baidu.com/image/pic/item/37d3d539b6003af3290eaf5d362ac65c1038b652.jpg"];
NSData *data = [NSData dataWithContentsOfURL:url];
UIImage *image = [UIImage imageWithData:data];
// 2.回到主线程设置图片
dispatch_async(XZMainQueue, ^{
NSLog(@"setting---%@ %@", [NSThread currentThread], image);
[self.button setImage:image forState:UIControlStateNormal];
});
});
}
@end
/*
* 打印结果
Test-GCD测试一下[873:44012] donwload---<NSThread: 0x7fc7a0401d50>{number = 2, name = (null)}
Test-GCD测试一下[873:43920] setting---<NSThread: 0x7fc7a0507930>{number = 1, name = main} <UIImage: 0x7fc7a0681530>, {440, 608}
*/
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