这里转载 给自己一个备份

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

案例一：

//
// 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

案例二：

//
// 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