UITextView 和 UITextField限制字符数和表情符号

UITextField限制字符数

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
    int pMaxLength = 12;
    NSInteger strLength = textField.text.length - range.length + string.length;
    if (strLength == pMaxLength) {
        [[PublicMethod alloc] toastWithTitle:@"达到限制字符数" andWiew:self.view andDelayTime:2 withFont:17];
    }
    //输入内容的长度 - textfield区域字符长度（一般=输入字符长度）+替换的字符长度（一般为0）
    return (strLength <= pMaxLength);
}

限制表情符号

+ (BOOL)stringContainsEmoji:(NSString *)string
{
    __block BOOL returnValue = NO;
    
    [string enumerateSubstringsInRange:NSMakeRange(0, [string length])
                               options:NSStringEnumerationByComposedCharacterSequences
                            usingBlock:^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *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) {
                                            returnValue = YES;
                                        }
                                    }
                                } else if (substring.length > 1) {
                                    const unichar ls = [substring characterAtIndex:1];
                                    if (ls == 0x20e3) {
                                        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;
                                    }
                                }
                            }];
    
    return returnValue;
}

UITextView限制字符数

//这个函数的最后一个参数text代表你每次输入的的那个字
- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text{
    if ([text isEqualToString:@"
"]){ //判断输入的字是否是回车，即按下return
        
        [textView endEditing:YES];
        return NO; //这里返回NO，就代表return键值失效，即页面上按下return，不会出现换行，如果为yes，则输入页面会换行
    }
    return textView.text.length + (text.length - range.length) <= 20;
}