iOS Development multithreading-Inter-thread communication

Cocoa provides 2 ways to communicate between iOS threads, 1 is performselector, and the other 1 is port.

First of all, the 1th kind, performselector, has the following several:

　　

The 2nd type is the Nsmachport way. Nsport has 3 subclasses, Nssocketport, Nsmessageport, Nsmachport, but only nsmachport available under iOS.

By registering nsmachport in the receive thread, using this port in another thread to send a message, the registered thread receives the message, and then eventually calls a callback function in the main thread.

As you can see, the result of using Nsmachport is 1 functions that call other threads, and that's exactly what Performselector does, so Nsmachport is a chicken. Inter-thread communication should be done through performselector.

The performance of inter-thread communication:

1 Threads pass data to another 1 threads

After performing a specific task in 1 threads, go to another 1 thread to continue the task

Here is an example of downloading a picture:

12345678910111213141516171819202122232425262728293031323334

@interface BTThreadViewController (){    UIImageView *imagev;}@end- (void)viewDidLoad{    [super viewDidLoad];        imagev = [[UIImageView alloc] initWithFrame:CGRectMake(100, 100, 100, 100)];    [self.view addSubview:imagev];        //子线程里面调用downImage方法下载图片    [self performSelectorInBackground:@selector(downImage) withObject:nil];}-(void)downImage{    //从网络中下载图片    NSURL *url = [NSURL URLWithString:@"http://i8.topit.me/8/c1/31/1142319854bdc31c18o.jpg"];    //将图片转换为二进制数据    NSData *imgData = [NSData dataWithContentsOfURL:url];    //数据转换成图片    UIImage *img = [UIImage imageWithData:imgData];         //回到主线程设置图片    [self performSelectorOnMainThread:@selector(senderImage:) withObject:img waitUntilDone:NO];}-(void)senderImage:(UIImage *)image{    imagev.image = image;}

iOS Development multithreading-Inter-thread communication