NSURLConnection代理的相关细节

NSURLConnection代理在子线程运行

NSURLConnection的代理默认是在主线程运行的

-(void)viewDidLoad
{
    NSString *strUrl = @"";
    
    strUrl = [strUrl stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
    
    NSURL *url = [NSURL URLWithString:strUrl];
    
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    
    NSURLConnection *con = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:YES];
    
    [con setDelegateQueue:[[NSOperationQueue alloc] init]];
}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    NSLog(@"%@", [NSThread currentThread]);
}

输出：{number = 1, name = main}

设置NSURLConnection的代理在子线程运行，须要执行 [con setDelegateQueue] 方法

-(void)viewDidLoad
{
    NSString *strUrl = @";
    
    strUrl = [strUrl stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
    
    NSURL *url = [NSURL URLWithString:strUrl];
    
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    
    NSURLConnection *con = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:YES];
    
    [con setDelegateQueue:[[NSOperationQueue alloc] init]];
}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    NSLog(@"%@", [NSThread currentThread]);
}

输出：{number = 3, name = (null)}

注：调用[con setDelegateQueue]方法，参数不能传递主线程，否则会卡死线程；

在子线程中执行NSURLConnection网络请求

-(void)viewDidLoad
{
    dispatch_async(dispatch_get_global_queue(0, 0), ^{
        NSString *strUrl = @"";
        
        strUrl = [strUrl stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
        
        NSURL *url = [NSURL URLWithString:strUrl];
        
        NSURLRequest *request = [NSURLRequest requestWithURL:url];
        
        [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:YES];
    });
}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    NSLog(@"%@", [NSThread currentThread]);
}

将网络请求放到子线程中执行，网络请求操做是不会执行的.这是由于NSURLConnection须要在RunLoop中执行，NSURLConnection 的start方法的注释中写到：若是在调用网络请求时没有指定RunLoop或operation queue，connection会被指定在当前线程的RunLoop的default模式中运行；

-(void)viewDidLoad
{
    dispatch_async(dispatch_get_global_queue(0, 0), ^{
        NSString *strUrl = @"";
        
        strUrl = [strUrl stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
        
        NSURL *url = [NSURL URLWithString:strUrl];
        
        NSURLRequest *request = [NSURLRequest requestWithURL:url];
        
        [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:YES];
    });
    
    //让当前线程的RunLoop运行起来
    [[NSRunLoop currentRunLoop] run]; 
}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    NSLog(@"%@", [NSThread currentThread]);
}