Question

这是my URL。我需要从这个URL获取数据..这将返回英文单词的值..但如果我给出像“ParaQuéVolviste”这样的参数..那么它返回null ..请帮助我..

我的代码是

 NSURLConnection * connectionGetISRC=[[NSURLConnection alloc]initWithRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://ws.spotify.com/search/1/track.json?q=Para Qué Volviste"]] delegate:self];
    [connectionGetISRC start];


-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    dataJson=[NSMutableData data];
}

-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    NSLog(@"dat %@",data);
    [dataJson appendData:data];
}

-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
    NSLog(@"error %@",error.description);
    [hud hide:YES];
}

-(void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    id dict=[NSJSONSerialization JSONObjectWithData:dataJson options:kNilOptions error:nil];
    NSLog(@"dataJson %@",dataJson);
    NSLog(@"dicvt %@",dict);
}

Answer 1

您应该在启动连接之前对请求参数进行编码，如下所示

NSString* urlString = [NSString stringWithFormat:@"http://ws.spotify.com/search/1/track.json?q=%@",[@"Para Qué Volviste" stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];

NSURL* url = [NSURL URLWithString:urlString];

NSURLConnection * connectionGetISRC=[[NSURLConnection alloc]initWithRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:url] delegate:self];
[connectionGetISRC start];

Answer 2

看起来您网址中的空格是个问题。试试这个连接字符串

 NSString *str=[NSString stringWithFormat:@"http://ws.spotify.com/search/1/track.json?q=Para Qué Volviste"];
str=[str stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
NSURLConnection * connectionGetISRC=[[NSURLConnection alloc]initWithRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:str]] delegate:self];
[connectionGetISRC start];

Answer 3

您希望百分比转义您的网址参数，但请注意不要被stringByAddingPercentEscapesUsingEncoding诱惑。这样可以很好地处理空间（这是当前的问题），但是如果你有一些其他的保留字符，它就会失败（例如，如果你的参数中包含&或+个字符，那就很明显了）。如果你想处理这些类型的字符，你真的应该使用CFURLCreateStringByAddingPercentEscapes代替：

NSString* urlString = [NSString stringWithFormat:@"http://ws.spotify.com/search/1/track.json?q=%@", [self percentEscapeString:@"Para Qué Volviste"]];
NSURLConnection * connectionGetISRC=[[NSURLConnection alloc]initWithRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:urlString] delegate:self];
// [connectionGetISRC start];

在哪里，percentEscapeString来电CFURLCreateStringByAddingPercentEscapes：

- (NSString *)percentEscapeString:(NSString *)string
{ 
    return CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault,
                                                                     (CFStringRef)string,
                                                                     NULL,
                                                                     (CFStringRef)@":/?@!$&'()*+,;=",
                                                                     kCFStringEncodingUTF8));
}

另外，initWithRequest:delegate:会自动启动连接，因此您不应手动调用start方法。 start的{{3}}表示：

仅当您使用initWithRequest:delegate:startImmediately:方法创建连接并为NO参数提供startImmediately时，才需要调用此方法。

NSURLConnection在某些参数中返回Null

3 个答案: