试图让数据从URL返回的数据为零的目标C

Question

我currentley试图从该链接检索数据：http://steamcommunity.com/market/priceoverview/?country=US&currency=3&appid=730&market_hash_name=%E2%98%85%20Bayonet

我想链路输出，当你去点击它的数据。

这里是我当前的代码：

NSData *data = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:@"http://steamcommunity.com/market/priceoverview/?country=US&currency=3&appid=730&market_hash_name=★%20Bayonet"]]; 

NSDictionary *test = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error]; 
NSLog(@"%@", test[@"lowest_price"]); 

但currentley它返回此错误：

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'data parameter is nil' 

我认为这是与所涉及的URL字符串中的明星，不任何人都有这个解决方案？

Answer 1

原来的网址，在示例代码，格式不正确。

首先，这里是工作的代码：

#import <Foundation/Foundation.h> 

int main(int argc, char *argv[]) { 
    @autoreleasepool { 
     NSError *error = nil; 

     // NOTE: I pruned the original '%20' in your example -- partially escaped strings 
     // are difficult to deal with. 
     NSString *urlString = @"http://steamcommunity.com/market/priceoverview/?country=US&currency=3&appid=730&market_hash_name=★ Bayonet"; 

     // Now, escape the entire string 
     NSURL *url = [NSURL URLWithString:[urlString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]]; 
     // Looks good 
     NSLog(@"%@", [url absoluteString]); 
     // http://steamcommunity.com/market/priceoverview/?country=US&currency=3&appid=730&market_hash_name=%E2%98%85%20Bayonet 

     // Run it 
     NSData *data = [[NSData alloc] initWithContentsOfURL:url]; 
     NSDictionary *test = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error]; 
     NSLog(@"%@", test[@"lowest_price"]); 
     //129,99&#8364; 
     // Data is weird to me, but looks appropriate. 
    } 
} 

首先，你没有尝试使用它之前逃脱的字符串。 initWithString: docs国家：

This method expects URLString to contain only characters that are allowed in a properly formed URL. All other characters must be properly percent escaped. Any percent-escaped characters are interpreted using UTF-8 encoding.

所以，我们这样做。但是，示例代码中的原始字符串“部分转义”。如果你逃脱了URL，你会结束：

http://steamcommunity.com/market/priceoverview/?country=US&currency=3&appid=730&market_hash_name=%E2%98%85%2520Bayonet 

，而不是

http://steamcommunity.com/market/priceoverview/?country=US&currency=3&appid=730&market_hash_name=%E2%98%85%20Bayonet 

...你可以看到，在 '％20' 将自身得到逃到“％2520 ”。

我希望这会有所帮助。干杯。

Answer 2

编辑： 请检查您复制的URL是否有错误。 实际的URL是您在评论中提到的： @“http://steamcommunity.com/market/priceoverview/?country=US&currency=3&appid=730&market_hash_name=%E2%98%85%20Bayonet”

NSData *data = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:@"http://steamcommunity.com/market/priceoverview/?country=US&currency=3&appid=730&market_hash_name=%E2%98%85%20Bayonet"]]; 
NSDictionary *test = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error]; 

NSLog(@"%@", test[@"lowest_price"]);