iOS NSDictionary 轉Json 去掉換行去掉空格

//dic 轉json 若是用系統自帶的會出現空格。
+ (NSString *)returnJSONStringWithDictionary:(NSDictionary *)dictionary{
    
    //系統自帶
    
    //    NSError * error;
    
    //    NSData * jsonData = [NSJSONSerialization dataWithJSONObject:dictionary options:kNilOptions error:&error];
    
    //    NSString * jsonStr = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
    
    //自定義
    
    NSString *jsonStr = @"{";
    
    NSArray * keys = [dictionary allKeys];
    
    for (NSString * key in keys) {
        
        jsonStr = [NSString stringWithFormat:@"%@\"%@\":\"%@\",",jsonStr,key,[dictionary objectForKey:key]];
        
    }
    
    jsonStr = [NSString stringWithFormat:@"%@%@",[jsonStr substringWithRange:NSMakeRange(0, jsonStr.length-1)],@"}"];
    
    return jsonStr;
    
}