UITextField只允许输入中,英文,数字

某些情况下要UITextField只能输入某一种特定的字符.比如大写A-Z或者小写a-z,或者汉字.或者数字. 这样的话使用NSPredicate正则表达式可以过滤 首先设置UItextField的代理 实现如下方法:

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
    
    if ([self isInputRuleAndNumber:string] || [string isEqualToString:@""]) {
        return YES;
    }
    return NO;
}

然后添加事件,因为选择输入法联想的词.是不会经过textField:shouldChangeCharactersInRange:replacementString:方法的

    [textField addTarget:self action:@selector(textFieldChanged:) forControlEvents:UIControlEventEditingChanged];

实现:

- (void)textFieldChanged:(UITextField *)textField {
    
    NSString *toBeString = textField.text;
    NSString *lastString;
    if(toBeString.length>0)
        lastString=[toBeString substringFromIndex:toBeString.length-1];

    if (![self isInputRuleAndNumber:toBeString]&&[self hasEmoji:lastString]) {
        textField.text = [self disable_emoji:toBeString];
        return;
    }
    NSString *lang = [[textField textInputMode] primaryLanguage];
    if([lang isEqualToString:@"zh-Hans"]) {
        UITextRange *selectedRange = [textField markedTextRange];
        UITextPosition *position = [textField positionFromPosition:selectedRange.start offset:0];
        if(!position) {
            NSString *getStr = [self getSubString:toBeString];
            if(getStr && getStr.length > 0) {
                textField.text = getStr;
            }
        }
    } else{
        NSString *getStr = [self getSubString:toBeString];
        if(getStr && getStr.length > 0) {
            textField.text= getStr;
        }
    }
}

再来实现限制:

pattern中,输入需要验证的通过的字符 小写a-z 大写A-Z 汉字\u4E00-\u9FA5 数字\u0030-\u0039

- (BOOL)isInputRuleAndNumber:(NSString *)str {
    NSString *pattern = @"[a-zA-Z\u4E00-\u9FA5\\u0030-\\u0039]";
    NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", pattern];
    BOOL isMatch = [pred evaluateWithObject:str];
    return isMatch;
}

实现判断是否是Emoji

- (BOOL)hasEmoji:(NSString*)str{
    NSString *pattern = @"[^\\u0020-\\u007E\\u00A0-\\u00BE\\u2E80-\\uA4CF\\uF900-\\uFAFF\\uFE30-\\uFE4F\\uFF00-\\uFFEF\\u0080-\\u009F\\u2000-\\u201f\r\n]";
    NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", pattern];
    BOOL isMatch = [pred evaluateWithObject:str];
    return isMatch;
}

字符限制

#define kMaxLength 20;
-(NSString *)getSubString:(NSString*)string
{
    NSStringEncoding encoding = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);
    NSData* data = [string dataUsingEncoding:encoding];
    NSInteger length = [data length];
    if (length > kMaxLength) {
        NSData *data1 = [data subdataWithRange:NSMakeRange(0, kMaxLength)];
        NSString *content = [[NSString alloc] initWithData:data1 encoding:encoding];
        if (!content || content.length == 0) {
            data1 = [data subdataWithRange:NSMakeRange(0, kMaxLength - 1)];
            content =  [[NSString alloc] initWithData:data1 encoding:encoding];
        }
        return content;
    }
    return nil;
}

参考资料:30分钟入门正则教程
https://share.weiyun.com/cecfd1aa61226d176875266801025b36