iphone - UITextField shouldChangeCharactersInRange委托(delegate)不起作用

我在创建新视图时遇到麻烦，我在注册视图上有一个UITextField和一个UIButton。

我从另一种观点称这种观点

//otherview.m

- (void)viewDidLoad
{
    [super viewDidLoad];

    RegistrationAlertViewController *regreg = [[RegistrationAlertViewController alloc] init];
    [self.view addSubview:regreg.view];

}

然后我像这样创建我的regregview

//regregView.h

#import <UIKit/UIKit.h>

@interface RegistrationAlertViewController : UIViewController <UITextFieldDelegate> {


    // textfields for registration
    IBOutlet UITextField *registrationTextFieldA;


}

// textfields for registration
@property (strong, nonatomic) IBOutlet UITextField *registrationTextFieldA;

@end

//regregView.m

#import "RegistrationAlertViewController.h"

@interface RegistrationAlertViewController ()

@end

@implementation RegistrationAlertViewController

@synthesize registrationTextFieldA;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    registrationTextFieldA = [[UITextField alloc] init];
    registrationTextFieldA.delegate = self;

    [registrationTextFieldA becomeFirstResponder];

    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField
{
    if([textField.text length] > 4)
    {
        //Get next TextField... A simple way to do this:
//        UITextField *newTextField = [textField.superview viewWithTag:(textField.tag+1)];
//        [newTextField becomeFirstResponder];
        return NO;
        //remember to set the tags in order
    }
    return YES; //you probably want to review this...
}

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    if((textField.text.length + string.length) > 4)
    {
        //Get next TextField... A simple way to do this:
//        UITextField *newTextField = [textField.superview viewWithTag:(textField.tag+1)];
//        [newTextField becomeFirstResponder];
        //remember to set the tags in order
    }
    return YES; //you probably want to review this...
}


@end

我的regregView.m中有两个代表


textFieldShouldBeginEditing
shouldChangeCharactersInRange


由于某些奇怪的原因，在视图第一次加载时会输入textFieldShouldBeginEditing，但是随后当我开始向registrationText中输入字符时，出于某些奇怪的原因，永远不会输入shouldChangeCharactersInRange。

非常感谢您弄清为什么我的代表不能正常工作的任何帮助。

最佳答案

在yourClass.h文件中包括UITextFielDelegate类别，然后尝试以下代码。

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

    int length = textField.text.length - range.length + string.length;
    if(length > 4)
    {
        return NO;
    }
    return YES;
}

- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField
{
    if([textField.text length] > 4)
    {
        return NO;
    }
    return YES; //you probably want to review this...
}

希望对您有帮助。

关于iphone - UITextField shouldChangeCharactersInRange委托(delegate)不起作用，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/17540096/