的TextField.text进入应该有特定的格式

Question

我有一个textfield，我想在这上面输入的格式文本： AA #### 1234 我知道这应该shouldChangeCharactersInRange委托方法来实现textfield .nut我无法理解每个角色的状态将如何实施。请给予您的建议。提前感谢！

Answer 1

，可以有助于验证您的需求的表达可能是：

^[a-z]{2}\s\d{4}\s\d{4}$ 

这里：

• ^ - 显示字符串
• [a-z]{2}的开始 - 显示A-Z之间的任何字符恰好2倍
• \s - 显示空白字符一次。
• \d{4} - 显示0-9的任何数字，正好4次。
• $ - 显示字符串

末作为一种解决方法的一个例子可能是这样，这里的棘手的部分是让施工串下：

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string 
{ 
    NSError *error = NULL; 
    NSRegularExpression *regex = nil; 

    NSMutableString *combinedText = [textField.text mutableCopy]; 
    [combinedText replaceCharactersInRange:range withString:string]; 

    switch (combinedText.length) { 
     case 1: 
     case 2: 
      regex = [NSRegularExpression regularExpressionWithPattern:[NSString stringWithFormat:@"^[a-z]{%ld}", (long)combinedText.length] options:NSRegularExpressionCaseInsensitive error:&error]; 
      break; 
     case 3: 
      regex = [NSRegularExpression regularExpressionWithPattern:@"^[a-z]{2}\\s" options:NSRegularExpressionCaseInsensitive error:&error]; 
      break; 
     case 4: 
     case 5: 
     case 6: 
     case 7: 
      regex = [NSRegularExpression regularExpressionWithPattern:[NSString stringWithFormat:@"^[a-z]{2}\\s\\d{%ld}", (long)combinedText.length - 3] options:NSRegularExpressionCaseInsensitive error:&error]; 
      break; 
     case 8: 
      regex = [NSRegularExpression regularExpressionWithPattern:@"^[a-z]{2}\\s\\d{4}\\s" options:NSRegularExpressionCaseInsensitive error:&error]; 
      break; 
     case 9: 
     case 10: 
     case 11: 
     case 12: 
      regex = [NSRegularExpression regularExpressionWithPattern:[NSString stringWithFormat:@"^[a-z]{2}\\s\\d{4}\\s\\d{%ld}$", (long)combinedText.length - 8] options:NSRegularExpressionCaseInsensitive error:&error]; 
      break; 
     default: 
      return false; 
    } 

    if(error) return false;   

    NSUInteger numberOfMatches = [regex numberOfMatchesInString:combinedText options:0 range:NSMakeRange(0, combinedText.length)]; 
    return numberOfMatches > 0 || string.length == 0; 
} 

希望帮助！

Answer 2

在UITextField上创建类别并根据您的要求添加此方法写入条件。下面的例子电子邮件ID：

- (BOOL)validateRegEx:(NSString*)regexString 
{ 
    NSError *error = NULL; 
    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:regexString 
                     options:NSRegularExpressionCaseInsensitive 
                     error:&error]; 
    NSUInteger numberOfMatches = [regex numberOfMatchesInString:self.text 
                options:0 
                 range:NSMakeRange(0, [self.text length])]; 

    return numberOfMatches > 0; 
} 

Answer 3

试试这个

-(BOOL)checkString:(NSString *)str{ 
    NSString *regex1 = @"^[a-bA-B0-9]"; // chabge regex as per your needs 
    NSPredicate *test1 = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex1]; 
    return [test1 evaluateWithObject:str] ; 
}