多线程 线程之间的通信

//  DYFViewController.m
//  623-06-线程间的通信
//
//  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 *imaV;

@end

@implementation DYFViewController

- ( void )viewDidLoad
{
    [ super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- ( void )touchesBegan:( NSSet *)touches withEvent:(UIEvent *)event
{
    // 1.下载图片
    [ self performSelector: @selector (download) withObject: nil ];

    // 显示、刷新界面，只能在主界面
    // 2.显示图片
}
/**
 *  下载图片：子线程
 */
- ( void )download
{
    // 1.根据URL下载图片
    NSURL *url = [ NSURL URLWithString:@ "http://image.cache.xiu8.com/live/125/125/997729.jpg" ];
    NSLog (@ "---------begin" );
    NSData *data = [ NSData dataWithContentsOfURL:url]; // 耗时

    NSLog (@ "-----------end" );

    UIImage *image = [UIImage imageWithData:data];

    // 2.回到主线程显示图片
//    [self.imaV performSelector:@selector(setImage:) onThread:[NSThread mainThread] withObject:image waitUntilDone:NO modes:nil];
    //[self performSelectorOnMainThread:@selector(settingImage:) withObject:nil waitUntilDone:NO];
    [ self .imaV performSelectorOnMainThread: @selector (setImage:) withObject:image waitUntilDone: NO ];
}
/**
 *  显示图片：主线程
 *
 *  @param image image
 */
- ( void )settingImage:(UIImage *)image
{
    self .imaV.image = image;
}

@end

 小结：主线程与子线程之间的通信