UITextField shouldChangeCharactersInRange代表不工作

Question

我遇到了一個新的視圖，我創建了一個註冊視圖，它有一個UITextField和一個UIButton。

我把這種觀點從另一種觀點認爲，像這樣

//otherview.m

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 

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

} 

然後創建我regregview這樣

//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 

我在regregView.m

• textFieldShouldBeginEditing
• shouldChangeCharactersInRange

兩個代表了一些奇怪的原因textFieldShouldBeginEditing是當視圖fi時輸入第一次加載，但然後當我開始輸入字符到registrationTextFieldAshouldChangeCharactersInRange永遠不會進入一些奇怪的原因。

任何幫助搞清楚爲什麼我的代表不能正常工作將不勝感激。

Answer 1

不要在viewDidLoad方法中分配UITextField實例。取而代之的是：

- (void)viewDidLoad 
{ 
    registrationTextFieldA.delegate = self; 
    [registrationTextFieldA becomeFirstResponder]; 
    [super viewDidLoad]; 
    // Do any additional setup after loading the view from its nib. 
} 

希望它能幫助你。

Answer 2

在yourClass.h文件中包含UITextFielDelegate類別並嘗試此代碼。

- (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... 
} 

我希望它可以幫助你。

Answer 3

這裏有個猜測。 問題是在你的otherview.m

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 

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

試着做RegistrationAlertViewController強大特性之上的otherview.m

@property (nonatomic, strong) RegistrationAlertViewController *regreg; 

然後在您的視圖做負載，你可以做

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 

    RegistrationAlertViewController *regreg = self.regreg; 
    if (regreg == nil) 
    { 
     self.regreg = [[RegistrationAlertViewController alloc] init]; 
    } 

    [self.view addSubview:regreg.view]; 

} 

希望有效..就好像我遇到過類似的問題..祝你好運

Answer 4

從你的xib插件添加UItextField委託並在你的.h文件中聲明委託協議<uitextfielddelegate>。

肯定它將很好地工作適合你。

好運!!!!

Answer 5

當你正在初始化視圖，而不是實現在viewDidLoad中在init方法本file.So集委託。

@synthesize registrationTextFieldA; 

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

    registrationTextFieldA = [[UITextField alloc] init]; 
    registrationTextFieldA.delegate = self; 
    [registrationTextFieldA becomeFirstResponder]; 

    } 
    return self; 
} 

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 
    // Do any additional setup after loading the view from its nib. 
}