ios - 验证用户输入的数字

Question

在我的应用程序中，我只想允许用户以“1111.11”格式输入十进制数。这意味着最多 4 位整数和最多 2 位十进制数我想在用户在文本框中编辑时检查这一点。如果用户输入错误的输入，则不应允许输入文本框。我已将代码写入:

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

方法，但虽然我没有得到想要的结果。这是我的代码

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
if (textField == txtFund)
{
    double num;
        long iPart;
        double fPart;
            num = [textField.text doubleValue];
            iPart = (long) num;
            fPart = num - iPart;
        NSLog(@"1 %ld %f",iPart,fPart);
        NSString *integerPart=[NSString stringWithFormat:@"%ld",iPart];

            if([integerPart length]>=4){
                if([string isEqualToString:@"."]){

                }
                else{
                return NO;
                }
            }
    NSString *newString = [textField.text stringByReplacingCharactersInRange:range withString:string];

    NSString *expression = @"^([0-9]+)?(\\.([0-9]{1,2})?)?$";

    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:expression
                                                                           options:NSRegularExpressionCaseInsensitive
                                                                             error:nil];
    NSUInteger numberOfMatches = [regex numberOfMatchesInString:newString
                                                        options:0
                                                          range:NSMakeRange(0, [newString length])];
    if (numberOfMatches == 0)
        return NO;
}

return YES;
 }

通过这段代码，我能够实现类似于“4444”的输出。但它不允许因为它在第二个 if 中转到 else 部分

Answer 1

这段代码应该做你想要的。

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

    NSString *newString = [textField.text stringByReplacingCharactersInRange:range withString:string];

    NSString *expression = @"^([0-9]{1,4})?(\\.([0-9]{1,2})?)?$";

    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:expression
                                                                           options:NSRegularExpressionCaseInsensitive
                                                                             error:nil];
    NSUInteger numberOfMatches = [regex numberOfMatchesInString:newString
                                                        options:0
                                                          range:NSMakeRange(0, [newString length])];
    if (numberOfMatches == 0)
        return NO;

    return YES;
}