【ios开发】输入时emoji表情过滤

开发中经常会遇到输入限制， 常用方法是设置keyboardType类型， 但是也会出现用户切换键盘输入emoji表情导致服务器提示服务异常的情况。

此时，输入过滤就尤为重要。

怎么过滤呢？

1. 添加字符串的类别方法

2. 在输入中进行过滤处理

创建一个NSStirng的类别， 添加如下两个方法：

#import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN

@interface NSString (FilterEmoji)

// 字符串过滤掉emoji
+ (NSString *)filterEmoji:(NSString *)string;

// 判断是否包含emoji
+ (BOOL)stringContainsEmoji:(NSString *)string;

@end


NS_ASSUME_NONNULL_END

在NSString+FilterEmoji.m文件中实现这两个方法：

#import "NSString+FilterEmoji.h"

@implementation NSString (FilterEmoji)

+ (NSString *)filterEmoji:(NSString *)string{
    __block NSString *newText = @"";
    
    BOOL isContainsEmoji = [NSString stringContainsEmoji:string];
    if (isContainsEmoji){
        if (string.length == 1){
            newText = [string substringToIndex:string.length - 1];
        }else{
            newText = [string substringToIndex:string.length - 2];
        }
    }else{
        newText = string;
    }
    
    return newText;
}

+ (BOOL)stringContainsEmoji:(NSString *)string{
    __block BOOL returnValue = NO;
    
    [string enumerateSubstringsInRange:NSMakeRange(0, string.length) options:NSStringEnumerationByComposedCharacterSequences usingBlock:^(NSString * _Nullable substring, NSRange substringRange, NSRange enclosingRange, BOOL * _Nonnull stop) {
        
        const unichar hs = [substring characterAtIndex:0];
        if (0xd800 <= hs && hs <= 0xdbff){
            if (substring.length > 1){
                const unichar ls = [substring characterAtIndex:1];
                const int uc = (hs - 0xd800) * 0x400 + (ls - 0xdc00) + 0x10000;
                if (0x1d000 <= uc && uc <= 0x1f77f){
                    // 有emoji;
                    returnValue = YES;
                }
            }
        }else if (substring.length > 1){
            const unichar ls = [substring characterAtIndex:1];
            if (ls == 0x20e3){
                // 有emoji
                returnValue = YES;
            }
        }else{
            if (0x2100 <= hs && hs <= 0x27ff){
                returnValue = YES;
            }else if (0x2B05 <= hs && hs <= 0x2b07){
                returnValue = YES;
            }else if (0x2934 <= hs && hs <= 0x2935){
                returnValue = YES;
            }else if (0x3297 <= hs && hs <= 0x3299){
                returnValue = YES;
            }else if (hs == 0xa9 || hs == 0xae || hs == 0x303d || hs == 0x3030 || hs == 0x2b55 || hs == 0x2b1c || hs == 0x2b1b || hs == 0x2b50 ){
                returnValue = YES;
            }else if (hs == 0x200d){
                returnValue = YES;
            }
        }
    }];
    
    return returnValue;
}

@end

在需要处理的类中导入NSString+FilterEmoji.h文件，实现UITextField或者UITextView的代理， （这里以UITextField为例）

先屏蔽系统键盘的emoji输入：

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(nonnull NSString *)string
{  
    if ([textField isFirstResponder])
    {
        if ([[[textField textInputMode] primaryLanguage] isEqualToString:@"emoji"] || ![[textField textInputMode] primaryLanguage])
        {
            return NO;
        }
    }
    
    return YES;
}

在UITextFieldTextDidChangeNotification或者UIControlEventEditingChanged方法中， 处理输入字符的过滤:

- (void)inputTextDidChange:(NSNotification *)notifi{
    
    UITextField *InputText = (UITextField *)[notifi object];
    
    NSString *text =InputText.text;
    // 过滤一下emoji
    if ([NSString stringContainsEmoji:text] == YES)
    {
        
        text = [NSString filterEmoji:text];
        
        InputText.text = text;
    }
}

仅记录自己常用方法，欢迎探讨。