data = [str dataUsingEncoding:NSUTF8StringEncoding];

NSError *error;

dic = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableLeaves error:&error];

NSLog(@"error === %@",error);

描述：json转换错误：Error Domain=NSCocoaErrorDomain Code=3840 "Unescaped control character around character 111." UserInfo={NSDebugDescription=Unescaped control character around character 111.}

原因：因为str中包含了制表符；

解决：

while ([str containsString:@"\r\n"]) {

str = [str stringByReplacingOccurrencesOfString:@"\r\n" withString:@""];

}

while ([str containsString:@"\t"]) {

str = [str stringByReplacingOccurrencesOfString:@"\t" withString:@""];

}

while ([str containsString:@"\n"]) {

str = [str stringByReplacingOccurrencesOfString:@"\n" withString:@""];

}

data = [str dataUsingEncoding:NSUTF8StringEncoding];

NSError *error;

dic = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableLeaves error:&error];

NSLog(@"error === %@",error);