無法更改UITextField的文本

Question

我已經以編程方式創建了2個UITextField和一個UIButton ，當我單擊UIButton我希望它更改突出顯示的UITextField的文本，但它更改的是第二個UITextField而不是突出顯示的UITextField的文本。

-(void)viewDidLoad
{
    txtf = [[UITextField alloc] initWithFrame:CGRectMake(0, 0, 586, 45)];
    txtf.borderStyle = UITextBorderStyleNone;
    txtf.backgroundColor = [UIColor clearColor];
    txtf.font = [UIFont systemFontOfSize:17];
    txtf.autocorrectionType = UITextAutocorrectionTypeNo;
    txtf.keyboardType = UIKeyboardTypeDefault;
    txtf.returnKeyType = UIReturnKeyDone;
    txtf.textAlignment = NSTextAlignmentLeft;
    txtf.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;
    [self.view addSubview:txtf];

    txtf = [[UITextField alloc] initWithFrame:CGRectMake(0, 0, 586, 345)];
    txtf.borderStyle = UITextBorderStyleNone;
    txtf.backgroundColor = [UIColor clearColor];
    txtf.font = [UIFont systemFontOfSize:17];
    txtf.autocorrectionType = UITextAutocorrectionTypeNo;
    txtf.keyboardType = UIKeyboardTypeDefault;
    txtf.returnKeyType = UIReturnKeyDone;
    txtf.textAlignment = NSTextAlignmentLeft;
    txtf.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;
    [self.view addSubview:txtf];
}

- (IBAction)change:(id)sender 
{
    txtf.text = @"the text was changed"
}

有什么辦法解決這個問題？

Answer 1

將您的代碼更改為

-(void)viewDidLoad{
txtf1 = [[UITextField alloc] initWithFrame:CGRectMake(0, 0, 586, 45)];
txtf1.borderStyle = UITextBorderStyleNone;
txtf1.backgroundColor = [UIColor clearColor];
txtf1.font = [UIFont systemFontOfSize:17];
txtf1.autocorrectionType = UITextAutocorrectionTypeNo;
txtf1.keyboardType = UIKeyboardTypeDefault;
txtf1.returnKeyType = UIReturnKeyDone;
txtf1.textAlignment = NSTextAlignmentLeft;
txtf1.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;
[self.view addSubview:txtf1];

txtf2 = [[UITextField alloc] initWithFrame:CGRectMake(0, 0, 586, 345)];
txtf2.borderStyle = UITextBorderStyleNone;
txtf2.backgroundColor = [UIColor clearColor];
txtf2.font = [UIFont systemFontOfSize:17];
txtf2.autocorrectionType = UITextAutocorrectionTypeNo;
txtf2.keyboardType = UIKeyboardTypeDefault;
txtf2.returnKeyType = UIReturnKeyDone;
txtf2.textAlignment = NSTextAlignmentLeft;
txtf2.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;
[self.view addSubview:txtf2];
}

- (IBAction)change:(id)sender {
txtf2.text = @"the text was changed"
}

並將txtf2添加到類成員。

更新 ：
要更改突出顯示的UITextField修改- (IBAction)change:(id)sender

- (IBAction)change:(id)sender 
{
    if ( txtf1.isHighlighted ) {
        txtf1.text = @"the text 1 was changed";
    }
    else if ( txtf2.isHighlighted ) {
        txtf2.text = @"the text 2 was changed";
    }  
    else {
        NSLog(@"none of the textField is Highlighted");
    }
}

更新2當您有很多文本字段時，您可以嘗試以下

for (id subview in self.view.subviews) {
    if ([subview isKindOfClass:[UITextField class]]) {
        UITextField *textField = subview;
        if (textField.isHighlighted) {
            textField.text = @"the text was changed";
        }
    }
}

Answer 2

txtf始終指向第二個textField。 這就是問題所在。

創建第一個UItextFied ， txtf指向它。 但是，當您創建一個新的UITextField並使txtf指向它時， 第一個textField的引用會丟失 。

在您的change方法中，您始終會獲得reference of second textfield的reference of second textfield並進行更改。

兩種選擇
1）使用txtf1和txtf2兩個類屬性
2）使用標簽。 [UIView viewWithTag:tagValue] ;

使用標簽->
假設您使用的numberOfTextFields為3。

txtf = [[UITextField alloc] initWithFrame:CGRectMake(0, 0, 586, 45)];
//set its properties
txtf.tag=1;
[self.view addSubview:txtf];

txtf = [[UITextField alloc] initWithFrame:CGRectMake(0, 0, 586, 45)];
//set its properties
txtf.tag=2;
[self.view addSubview:txtf];

txtf = [[UITextField alloc] initWithFrame:CGRectMake(0, 0, 586, 45)];
//set its properties
txtf.tag=3;
[self.view addSubview:txtf];

修改更改方法為

- (IBAction)change:(id)sender
{
    NSInteger numberOfTextFields=3;
    UITextField *textField;
    for (int i=1; i<=numberOfTextFields; i++) {
        textField=(UITextField*)[self.view viewWithTag:i];
        if(textField.isHighlighted==YES)
            break;
        else
            textField=nil;
    }

    if(textField==nil){
        NSLog(@"none is highlightes");
    }
    else{
        textField.text= @"new text for highlighted textField";
    }
}

Answer 3

因為兩個UITextField名稱都相同（txtf） ，所以請首先更改第一個或第二個UITextField的名稱。 否則您的代碼是正確的。 :)

編輯：

只要做出更正確的@Avt更新后的答案即可。

- (IBAction)change:(id)sender 
{
    if ( txtf1.isHighlighted ) {
        txtf1.text = @"the text 1 was changed";
    }
    else if ( txtf2.isHighlighted ) {
        txtf2.text = @"the text 2 was changed";
    }  
    else {
        NSLog(@"none of the textField is Highlighted");
    }
}