Ios NSURLConnection在某些参数中返回Null

这是。我需要从这个URL获取数据。它将返回英文单词的值。但是如果我给参数“Para QuéVolviste”。那么它将返回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);
}

---

在初始化连接之前，您应该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];

---

在初始化连接之前，您应该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];

---

看起来URL中的空格是个问题。请尝试此连接

 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];

---

看起来URL中的空格是个问题。请尝试此连接

 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];

---

您希望百分比转义URL的参数，但请注意不要被

stringby添加百分比转义usingencode

所诱惑。这可以很好地处理空格（这是一个直接的问题），但如果其中有一些其他保留字符，则会失败（例如，如果您的参数中有

&

或

+

字符）。如果要处理这些类型的字符，确实应该使用

CFURLCreateStringByAddingPercentEscapes

：

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];

其中，

percentEscapeString

调用

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，因此您不应该手动调用

start

方法。至于

start

说：

仅当您使用

initWithRequest:delegate:startImmediately:

方法创建连接并为

startImmediately

参数提供

NO

时，才需要调用此方法

---

您希望百分比转义URL的参数，但请注意不要被

stringby添加百分比转义usingencode

所诱惑。这可以很好地处理空格（这是一个直接的问题），但如果其中有一些其他保留字符，则会失败（例如，如果您的参数中有

&

或

+

字符）。如果要处理这些类型的字符，确实应该使用

CFURLCreateStringByAddingPercentEscapes

：

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];

其中，

percentEscapeString

调用

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，因此您不应该手动调用

start

方法。至于

start

说：

仅当您使用

initWithRequest:delegate:startImmediately:

方法创建连接并为

startImmediately

参数提供

NO

时，才需要调用此方法