字符串相关操作

 

// 表情映射。
                NSString *didReceiveText = [ConvertToCommonEmoticonsHelper
                                            convertToSystemEmoticons:((EMTextMessageBody *)messageBody).text];
                NSString *temp = nil;
                NSString *newtemp = @"" ;
                //便利字符串.
                for (int i = 0; i<didReceiveText.length; i++) {
                    if ([didReceiveText characterAtIndex:i] == '[' && i+8<didReceiveText.length) {
                          temp = [didReceiveText substringWithRange:NSMakeRange(i, 9)];//截取字符串从下标i开始往后截取8位
                        if([temp rangeOfString:@"exp_"].location !=NSNotFound){ //判断是否存在
                            newtemp =  [newtemp stringByAppendingString:@"[表情]"]; //字符串拼接
                        }
                        i+=8;//调整索引
                    }
                    else{
                        newtemp = [newtemp stringByAppendingString:[didReceiveText substringWithRange:NSMakeRange(i, 1)]];
                    }
                }
                结果= newtemp;