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];
}
这就是我得到回应时所做的。
- (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]);
}
}
这是我的装载数据代码
-(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);
这是我的背景流程
-(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];
}
我不知道哪里做错了，谁能指引我？
我希望后台进程一直运行，直到它收到数据，当数据接收到appdel时。isExists变为现实
我试过GCD
它与NSURLSessionDownloadTask一起工作，但仍在寻找更好的选项。
不要在后台调用NSURLConnection。AsNSURLConnection将自动工作。由于您不发送异步请求，它将在后台工作，并且不会挂起主线程。在加载数据中删除分派。你有：
if (temp)
{
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{
[self backgroundProcess];
});
}
成功：
if (temp)
{
[self backgroundProcess];
}
您不需要使用调度。
要从服务器加载UIImageView中的图像，可以使用以下框架。
SDWebImage
您将获得completionBlock，progressBlock
样本：
如果imageURL有效（这是您的情况），则只需加载图像，这与此代码一样简单
UIImageView *imageView;
[imageView setImageWithURL:[NSURL URLWithString:YOUR_URL]];
它也有丰富的方法，如下所示
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 ...
}];
