json解析出錯誤？

1. 編碼問題。

2. 如果data是有數據的，但是arr是nil，找到error:The operation couldn't be completed. (Cocoa error 3840.)NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:urlString]];NSError *error = nil;NSStringEncoding enc = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);NSString *dataString = [[NSString alloc] initWithData:data encoding:enc];NSData *utf8Data = [dataString dataUsingEncoding:NSUTF8StringEncoding];NSArray *arr = [NSJSONSerialization JSONObjectWithData:utf8Data options:NSJSONReadingMutableContainers error:&error];

3. json非標準格式：（比如json數據存在\n \r \t 等制表符）

NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:urlString]];

NSError *error = nil;NSStringEncoding enc = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);NSString *dataString = [[NSString alloc] initWithData:data encoding:enc];//json數據當中沒有 \n \r \t 等制表符，當后臺給出有問題時，我們需要對json數據過濾 dataString = [dataString stringByReplacingOccurrencesOfString:@"\r\n" withString:@""]; dataString = [dataString stringByReplacingOccurrencesOfString:@"\n" withString:@""]; dataString = [dataString stringByReplacingOccurrencesOfString:@"\t" withString:@""]; NSData *utf8Data = [dataString dataUsingEncoding:NSUTF8StringEncoding];NSArray *arr = [NSJSONSerialization JSONObjectWithData:utf8Data options:NS