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：

#import "CKViewController.h" 
@interface CKViewController () 
@property (weak, nonatomic) IBOutlet UIImageView *iconView;  
@end  

@implementation CKViewController 

- (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：

#import "CKViewController.h" 
#import <NSData.h> 

@interface CKViewController () 
@property (weak, nonatomic) IBOutlet UIImageView *iconView;  
@end  

@implementation CKViewController 

- (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