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事情 .
- (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];
}
我不知道我哪里做错了,任何人都可以指导我吗?
我希望后台进程继续运行,直到它获取数据,当收到数据时,appdel.isExists变为true并获取主线程以更新ui .
我尝试了GCD& performSelectorInTheBackground
但我没有做对,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 .
2 回答
要从服务器加载
UIImageView
中的映像,可以使用以下框架 .SDWebImage
您将获得
completionBlock
,progressBlock
以及可用于更新UI的更多属性 . 它会以块的形式通知您,然后您可以在UI上更新您想要的任何内容 .样品:
如果
imageURL
有效(这是你的情况),只需加载图像就像这段代码一样简单它也有如下丰富的方法
不要在后台调用
NSURLConnection
. 由于NSURLConnection
将自动运行 . 由于您没有发送异步请求,因此它将在后台运行,并且不会挂起您的主线程 . 在您的加载数据中删除调度 . 你有:做了:
您不需要使用派遣 .