UITextField文字字数检验方法

邮箱校验

 NSString *emailRegex = @"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789@._-%+-";
 NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegex];
 if ([emailTest evaluateWithObject:textField.text]) {
       
 }else{
       
 }

或者

 NSString *emailRegex = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}";
 NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegex];
 if ([emailTest evaluateWithObject:textField.text]) {
       
 }else{
       
 }

中文检验

    NSString *regex =@"[\u4e00-\u9fa5]+";
    NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",regex];

只允许输入字母数字

    NSString *regex =@"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
    NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",regex];

中文输入时字数限制

添加监听

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChange:) name:UITextFieldTextDidChangeNotification object:nil];

实现方法

- (void)textChange:(NSNotification*)noti {

// 拿到文本改变的 text field
UITextField *textField = (UITextField *)noti.object;

// 需要限制的长度
NSUInteger maxLength = 0;
if (textField == _companyTextField) {
    maxLength = 20;
    
}

if (textField == _jobTextField) {
    maxLength = 10;
}
if (maxLength == 0) return;

// text field 的内容
NSString *contentText = textField.text;

// 获取高亮内容的范围
UITextRange *selectedRange = [textField markedTextRange];
// 这行代码 可以认为是 获取高亮内容的长度
NSInteger markedTextLength = [textField offsetFromPosition:selectedRange.start toPosition:selectedRange.end];
// 没有高亮内容时,对已输入的文字进行操作
if (markedTextLength == 0) {
    // 如果 text field 的内容长度大于我们限制的内容长度
    if (contentText.length > maxLength) {
        // 截取从前面开始maxLength长度的字符串
        //            textField.text = [contentText substringToIndex:maxLength];
        // 此方法用于在字符串的一个range范围内，返回此range范围内完整的字符串的range
        NSRange rangeRange = [contentText rangeOfComposedCharacterSequencesForRange:NSMakeRange(0, maxLength)];
        textField.text = [contentText substringWithRange:rangeRange];
    }
}
}

移除监听

-(void)dealloc{
[[NSNotificationCenter defaultCenter] removeObserver:self];
}

字数检验

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{

NSMutableString *newtext = [NSMutableString stringWithString:textField.text];
[newtext replaceCharactersInRange:range withString:string];


/*
if (textField == _companyTextField) {
    if ([newtext length] > 20) {
        EPShowSuccess(@"公司名称不能超过20字");
        return NO;
    }
}

if (textField == _jobTextField) {
    if ([newtext length] > 10) {
        EPShowSuccess(@"职位名称不能超过10字");
        return NO;
    }
}

 */
return YES;
}

谓词校验

NSPredicate使用