Question

我正在发送异步http GET请求，并正确调用completionHandler。像NSLog这样的回调中的代码会运行，因为我可以看到日志中的输出。但是，行：self.imageView.image = nil;在NSLog语句“到达这里”几秒钟后似乎没有生效。有谁知道发生了什么？示例代码如下：

在ViewController.m中：

@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIImageView *imageView;
@end

@implementation ViewController
@synthesize imageView = _imageView;

-void viewDidLoad {
    // ImageView
    UIImage *image = [UIImage imageNamed:@"test.jpg"];
    self.imageView.backgroundColor = [UIColor blackColor];
    self.imageView.clipsToBounds = YES;
    self.imageView.image = image;
}

-void test {

    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"http://someurl"] cachePolicy:NSURLRequestReloadIgnoringLocalAndRemoteCacheData timeoutInterval:10];
    [request setHTTPMethod:@"GET"];
    NSOperationQueue *queue = [[NSOperationQueue alloc] init];
    [NSURLConnection sendAsynchronousRequest:request queue:queue
completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
        self.imageView.image = nil;
        NSLog(@"got here");
    }];
}

@end

Answer 1

啊，看起来像将队列参数设置为[NSOperationQueue mainQueue]固定在这里：

NSURLConnection sendAsynchronousRequest:queue:completionHandler: making multiple requests in a row?

Answer 2

正如Undept建议的那样，在主线程上调用thous行。像这样：

dispatch_async (dispatch_get_main_queue (),  ^{
self.imageView2.image = nil;
self.imageView.image = nil;
});

iOS：NSURLConnection sendAsynchronousRequest在NSImageView上的延迟操作

2 个答案: