NSThread线程间通信

线程间通信：1.一个线程传递数据给另一个线程 2.一个线程执行完任务后转到下一个线程继续执行任务。

常用方法：

- (void)performSelectorOnMainThread:(SEL)aSelector withObject:(nullableid)arg waitUntilDone:(BOOL)wait modes:(nullableNSArray *)array;

- (void)performSelectorOnMainThread:(SEL)aSelector withObject:(nullableid)arg waitUntilDone:(BOOL)wait;// equivalent to the first method with kCFRunLoopCommonModes

小例子：图片下载

#import"ViewController.h"

@interfaceViewController()

@property(weak,nonatomic)IBOutletUIImageView*imageView;

@end

@implementationViewController

#pragma mark ----------------------

#pragma Events

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent*)event

{

[NSThreaddetachNewThreadSelector:@selector(download)toTarget:selfwithObject:nil];

}

#pragma mark ----------------------

#pragma Methods

//开子线程下载图片,回到主线程刷新UI

-(void)download

{

//1.确定URL

NSURL*url = [NSURLURLWithString:@"http://img4.duitang.com/uploads/blog/201310/18/20131018213446_smUw4.thumb.700_0.jpeg"];

//2.根据url下载图片二进制数据到本地

NSData*imageData = [NSDatadataWithContentsOfURL:url];

//3.转换图片格式

UIImage*image = [UIImageimageWithData:imageData];

NSLog(@"download----%@",[NSThreadcurrentThread]);

//4.回到主线程显示UI

/*

第一个参数:回到主线程要调用哪个方法

第二个参数:前面方法需要传递的参数此处就是image

第三个参数:是否等待

*/

//[self performSelectorOnMainThread:@selector(showImage:) withObject:image waitUntilDone:NO];

//[self performSelector:@selector(showImage:) onThread:[NSThread mainThread] withObject:image waitUntilDone:YES];

[self.imageViewperformSelectorOnMainThread:@selector(setImage:)withObject:imagewaitUntilDone:YES];

//self.imageView.image = image;

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

}

//计算代码段执行时间的第一种方法

-(void)download1

{

//0.000018

//0.166099

//1.确定URL

NSURL*url = [NSURLURLWithString:@"http://img4.duitang.com/uploads/blog/201310/18/20131018213446_smUw4.thumb.700_0.jpeg"];

NSDate*start = [NSDatedate];//获得当前的时间

//2.根据url下载图片二进制数据到本地

NSData*imageData = [NSDatadataWithContentsOfURL:url];

NSDate*end = [NSDatedate];//获得当前的时间

NSLog(@"%f",[endtimeIntervalSinceDate:start]);

//3.转换图片格式

UIImage*image = [UIImageimageWithData:imageData];

//4.显示UI

self.imageView.image= image;

}

//计算代码段执行时间的第二种方法

-(void)download2

{

//1.确定URL

NSURL*url = [NSURLURLWithString:@"http://img4.duitang.com/uploads/blog/201310/18/20131018213446_smUw4.thumb.700_0.jpeg"];

CFTimeIntervalstart =CFAbsoluteTimeGetCurrent();

//2.根据url下载图片二进制数据到本地

NSData*imageData = [NSDatadataWithContentsOfURL:url];

CFTimeIntervalend =CFAbsoluteTimeGetCurrent();

NSLog(@"end-start = %f---%f---%f",end - start,end,start);

//3.转换图片格式

UIImage*image = [UIImageimageWithData:imageData];

//4.显示UI

self.imageView.image= image;

}

//更新UI操作

-(void)showImage:(UIImage*)image

{

self.imageView.image= image;

NSLog(@"UI----%@",[NSThreadcurrentThread]);

}