ios - 如何限制 UIAlertView UITextField 中的字符输入

Question

我正在尝试限制允许我的用户在我的 UIAlertView 中输入我的 UITextField 的字符数。

我尝试了网络上的一些常见答案。如下图所示:

  #define MAXLENGTH 10


- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    if ([textField.text length] > MAXLENGTH) {
        textField.text = [textField.text substringToIndex:MAXLENGTH-1];
        return NO;
    }
    return YES;
}

有人能帮忙吗？

Answer 1

.h文件

  @property (strong,nonatomic)  UITextField *alertText;

@interface LocationSearchViewController : UIViewController<UITextFieldDelegate>

.m 文件

- (IBAction)butPostalCode:(id)sender {

UIAlertView *alrt=[[UIAlertView alloc]initWithTitle:@"" message:@"" delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:@"OK", nil];
alrt.alertViewStyle = UIAlertViewStylePlainTextInput;
[[alrt textFieldAtIndex:0] setPlaceholder:@"Enter postal Code"];
alertText = [alrt textFieldAtIndex:0];
alertText.keyboardType = UIKeyboardTypeNumberPad;
alertText.delegate=self;
alrt.tag=100;
[alrt show];
}



-(BOOL) textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
if(yourtextfieldname.text.length >= 10 && range.length == 0) {
    return NO;

}
return YES;
}

swift

class LocationSearchViewController: UIViewController, UITextFieldDelegate {

 Var alertText:UITextField!
}

func butPostalCode(sender: AnyObject) {
var alrt: UIAlertView = UIAlertView(title: "", message: "", delegate: self, cancelButtonTitle: "Cancel", otherButtonTitles: "OK")
alrt.alertViewStyle = .PlainTextInput
alrt.textFieldAtIndex(0).placeholder = "Enter postal Code"
alertText = alrt.textFieldAtIndex(0)
alertText.keyboardType = .NumberPad
alertText.delegate = self
alrt.tag = 100
alrt.show()
}

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
if yourtextfieldname.text.length >= 10 && range.length == 0 {
    return false
}
return true
}