用while循环加载setbackground
我正在使用以下代码检查网址的应用程序。
-(void)exists { NSString *strImg = @"some url"; NSURL *aImgUrl = [NSURL URLWithString:strImg]; NSMutableURLRequest *imgRequest = [NSMutableURLRequest requestWithURL:strImg]; [imgRequest setHTTPMethod:@"HEAD"]; imgConnection = [NSURLConnection connectionWithRequest:imgRequest delegate:self]; }
当我得到回应时,这就是我所做的。
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response { if ([(NSHTTPURLResponse *)response statusCode] == 200) { // url exists appDel.isExists = TRUE; temp = FALSE; [self loadData]; NSLog(@"%ld",(long)[(NSHTTPURLResponse *)response statusCode]); } else if([(NSHTTPURLResponse*)response statusCode] == 404) { //url does not exists appDel.isExists = FALSE; temp = TRUE; [self loadData]; NSLog(@"%ld",(long)[(NSHTTPURLResponse *)response statusCode]); } }
这是我的加载数据代码
-(void)loadData { result = FALSE; isReqSent = FALSE; do { if (appDel.isExists == TRUE) { NSURL *aTxtUrl = [NSURL URLWithString:apiText]; NSURL *aImgUrl = [NSURL URLWithString:apiImage]; NSURLRequest *imgRequest = [NSURLRequest requestWithURL:aImgUrl]; NSURLRequest *txtRequest = [NSURLRequest requestWithURL:aTxtUrl]; [NSURLConnection sendAsynchronousRequest:txtRequest queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) { if (data) { NSString *strTxt = [[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding]; [lblTime setText:strTxt]; [policyImgWebView loadRequest:imgRequest]; result = TRUE; } }]; } if (result) { appDel.isExists = TRUE; } else { if(!isReqSent) { NSString *soapMessage = @"my soap message"; NSString *soapAction = @"my soap url"; [objWebServiceParser xmlParsing:soapMessage :soapAction :Number]; isReqSent = TRUE; } } if (temp) { dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{ [self backgroundProcess]; }); } } while (result == FALSE);
这是我的后台进程
-(void)backgroundProcess { NSString *strImg = @"some url"; NSURL *aImgUrl = [NSURL URLWithString:apiImage]; NSMutableURLRequest *imgRequest = [NSMutableURLRequest requestWithURL:aImgUrl]; [imgRequest setHTTPMethod:@"HEAD"]; imgConnection = [NSURLConnection connectionWithRequest:imgRequest delegate:self]; }
我不知道我在做错什么,可以有人指导我吗?
我想要后台进程保持运行,直到它获取数据,当数据收到appdel.isExists变为真并获取主线程来更新ui。
我试过GCD& performSelectorInTheBackground
但我没有得到它的权利,我得到NSThread
失败错误35。
它与NSURLSessionDownloadTask一起工作,但仍在寻找更好的选择。
要从服务器加载UIImageView
的图像,可以使用下面的框架。
SDWebImage
您可以获得completionBlock
, progressBlock
更多可用于更新UI的属性。 它会以块形式通知您,然后您可以在UI上更新任何您想要的内容。
样品:
这与代码一样简单,只要imageURL
有效就可以加载图像(这是您的情况)
UIImageView *imageView;
[imageView setImageWithURL:[NSURL URLWithString:YOUR_URL]];
它也有如下丰富的方法
UIImageView *imageView;
[imageView setImageWithURL:[NSURL URLWithString:YOUR_URL]
placeholderImage:[UIImage imageNamed:@"placeholder.png"]
completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType)
{
// in "image" you'll get the downloaded image from the URL
... completion code here ...
}];
不要在后台调用NSURLConnection
。 由于NSURLConnection
将自动工作。 由于您没有发送异步请求,它将在后台运行并且不会挂起主线程。 在您的负载数据中删除调度。 你有:
if (temp)
{
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{
[self backgroundProcess];
});
}
做了:
if (temp)
{
[self backgroundProcess];
}
你不需要使用派遣。
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