iOS开发多线程篇—线程间的通信

Posted 2020-07-21 快乐加油站789

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