如何通過多個UITextFields

Question

我有四個UITextFields，我想在UIAlertView中使用步驟，目前這是它看起來像

我想做什麼就能做的是一旦達到4個字符的限制，每個字段限制每個字段爲4個字符，然後我希望下一個UITextField成爲第一個響應者。

我也想能夠做到這一點反向，所以如果字符被刪除，一旦沒有在第二場可用字符到第一，並開始刪除等

目前我的代碼是非常馬虎，因爲我只是想得到像這樣的工作..所以這是它看起來像迄今爲止。

//提示用戶輸入註冊在這裏 UIAlertView中*警報= [[UIAlertView中頁頭] initWithTitle：@ 「請註冊設備」 消息：@ 「 」代表：無cancelButtonTitle：@「 OK」 otherButtonTitles：無]。

UITextField *myTextField = [[UITextField alloc] initWithFrame:CGRectMake(12, 45, 53, 30)]; 

UITextField *myTextField1 = [[UITextField alloc] initWithFrame:CGRectMake(77, 45, 53, 30)]; 
UITextField *myTextField2 = [[UITextField alloc] initWithFrame:CGRectMake(142, 45, 53, 30)]; 
UITextField *myTextField3 = [[UITextField alloc] initWithFrame:CGRectMake(207, 45, 53, 30)]; 

// need to do something with first reasponder once 4 digits has been entered per box etc. 
[myTextField becomeFirstResponder]; 

myTextField.placeholder =@"AAAA"; 
myTextField.autocapitalizationType = UITextAutocapitalizationTypeAllCharacters; 
myTextField.textAlignment = NSTextAlignmentCenter; 
myTextField.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter; 

myTextField1.placeholder =@"AAAA"; 
myTextField1.autocapitalizationType = UITextAutocapitalizationTypeAllCharacters; 
myTextField1.textAlignment = NSTextAlignmentCenter; 
myTextField1.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter; 

myTextField2.placeholder =@"AAAA"; 
myTextField2.autocapitalizationType = UITextAutocapitalizationTypeAllCharacters; 
myTextField2.textAlignment = NSTextAlignmentCenter; 
myTextField2.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter; 

myTextField3.placeholder =@"AAAA"; 
myTextField3.autocapitalizationType = UITextAutocapitalizationTypeAllCharacters; 
myTextField3.textAlignment = NSTextAlignmentCenter; 
myTextField3.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter; 

[myTextField setBackgroundColor:[UIColor whiteColor]]; 
[myTextField1 setBackgroundColor:[UIColor whiteColor]]; 
[myTextField2 setBackgroundColor:[UIColor whiteColor]]; 
[myTextField3 setBackgroundColor:[UIColor whiteColor]]; 

[alert addSubview:myTextField]; 
[alert addSubview:myTextField1]; 
[alert addSubview:myTextField2]; 
[alert addSubview:myTextField3]; 

[alert show]; 

任何幫助將不勝感激。

// UPDATE： 這是我想使用的委託方法

//.h 
<UITextFieldDelegate> 

//.m 
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 
{ 
//.. 
    [self.myTextField setDelegate:self]; 
    [self.myTextField1 setDelegate:self]; 
    [self.myTextField2 setDelegate:self]; 
    [self.myTextField3 setDelegate:self]; 
//.. 
} 

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string { 
    NSLog(@"yay"); 
    return NO; 
} 

Answer 1

更新

我嘗試下面的代碼，並沒有工作，但如果你改變了FirstResponder一個原因，文本將不會被寫入。所以我修改了這個功能。你應該這樣做：

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

    if((textField.text.length + string.length) >= MAX_LENGTH) 
    { 
     int currentTag = textField.tag; 

     if(currentTag == 4) 
      return YES; 

     UITextField *newTextField = (UITextField *) [textField.superview viewWithTag:(currentTag+1)]; 
     [newTextField becomeFirstResponder]; 
     textField.text = [textField.text stringByAppendingString:string]; 
    } 
    return YES; //you probably want to review this... 
} 

任何方式，當你wan't刪除內容，這並不工作，但很容易，如果你改變了代碼來檢查的變化範圍內解決。

我做了一個樣本項目，你可以在這裏：TextFieldTest

---

這是我會怎麼做，使用文本框的委託，可以檢查新插入的字符，如果達到最大，你移動到下一個文本框：

static int MAX_LENGTH = 4; 
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string 
{ 
    if((textField.text.length + string.length) >= MAX_LENGTH) 
    { 
     //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... 
} 

（很抱歉，如果這麼想的編譯我只是寫在這裏直接）

祝您好運！

Answer 2

您可以爲這些文本字段設置委託，並實現業務邏輯（設置文本字段作爲新的一個第一響應者）在委託方法中。