iOS开发多线程篇—线程间的通信

iOS开发多线程篇—线程间的通信

一、简单说明

线程间通信：在1个进程中，线程往往不是孤立存在的，多个线程之间需要经常进行通信

线程间通信的体现

1个线程传递数据给另1个线程

在1个线程中执行完特定任务后，转到另1个线程继续执行任务

线程间通信常用方法

– (void)performSelectorOnMainThread:(SEL)aSelector withObject:(id)arg waitUntilDone:(BOOL)wait;

– (void)performSelector:(SEL)aSelector onThread:(NSThread *)thr withObject:(id)arg waitUntilDone:(BOOL)wait;

线程间通信示例 – 图片下载

代码1：

 //
 //  YYViewController.m
 //  06-NSThread04-线程间通信
 //
 //  Created by apple on 14-6-23.
 //  Copyright (c) 2014年 itcase. All rights reserved.
 // #import "YYViewController.h"
 @interface YYViewController ()
 @property (weak, nonatomic) IBOutlet UIImageView *iconView;
 @end @implementation YYViewController - (void)viewDidLoad
 {
     [super viewDidLoad];
 } -(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
 { // 在子线程中调用download方法下载图片
     [self performSelectorInBackground:@selector(download) withObject:nil];
 } -(void)download
 {
     //1.根据URL下载图片
     //从网络中下载图片
     NSURL *urlstr=[NSURL URLWithString:@"fdsf"];     //把图片转换为二进制的数据
     NSData *data=[NSData dataWithContentsOfURL:urlstr];//这一行操作会比较耗时     //把数据转换成图片
     UIImage *image=[UIImage imageWithData:data];     //2.回到主线程中设置图片
     [self performSelectorOnMainThread:@selector(settingImage:) withObject:image waitUntilDone:NO];
 } //设置显示图片
 -(void)settingImage:(UIImage *)image
 {
     self.iconView.image=image;
 } @end

代码2：

 //
 //  YYViewController.m
 //  06-NSThread04-线程间通信
 //
 //  Created by apple on 14-6-23.
 //  Copyright (c) 2014年 itcase. All rights reserved.
 // #import "YYViewController.h"
 #import <NSData.h> @interface YYViewController ()
 @property (weak, nonatomic) IBOutlet UIImageView *iconView;
 @end @implementation YYViewController - (void)viewDidLoad
 {
     [super viewDidLoad];
 } -(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
 {
 // 在子线程中调用download方法下载图片     [self performSelectorInBackground:@selector(download) withObject:nil];
 } -(void)download
 {     //1.根据URL下载图片
     //从网络中下载图片
     NSURL *urlstr=[NSURL URLWithString:@"fdsf"];     //把图片转换为二进制的数据
     NSData *data=[NSData dataWithContentsOfURL:urlstr];//这一行操作会比较耗时     //把数据转换成图片
     UIImage *image=[UIImage imageWithData:data];     //2.回到主线程中设置图片
     //第一种方式
 //    [self performSelectorOnMainThread:@selector(settingImage:) withObject:image waitUntilDone:NO];     //第二种方式
     //    [self.imageView performSelector:@selector(setImage:) onThread:[NSThread mainThread] withObject:image waitUntilDone:NO];     //第三种方式
    [self.iconView performSelectorOnMainThread:@selector(setImage:) withObject:image waitUntilDone:NO];
 } //设置显示图片
 //-(void)settingImage:(UIImage *)image
 //{
 //    self.iconView.image=image;
 //} @end