xcode 如何隐藏特定文本字段输入的标签？
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How to hide a label for specific text field input?
提问by J.Vongehr
I′ve created a Xcode project with just one button, one text field and one label. I want to make the label only visible, when the text field input is "test123" or the button gets pressed. The part with the button works well, but no matter what i type in the textfield, the label stays hidden. Anyone help? This is my current code:
我创建了一个只有一个按钮、一个文本字段和一个标签的 Xcode 项目。我想让标签仅在文本字段输入为“test123”或按钮被按下时可见。带有按钮的部分运行良好，但无论我在文本字段中输入什么，标签都会保持隐藏状态。有人帮忙吗？这是我当前的代码：
import UIKit
class ViewController: UIViewController, UITextFieldDelegate {
@IBOutlet weak var Label: UILabel!
@IBOutlet weak var Examplefield: UITextField!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
Label.hidden = true
Examplefield.resignFirstResponder()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
@IBAction func ButtonPressed(sender: UIButton) {
Label.hidden = false
}
func textFieldDidEndEditing(textField: UITextField) {
if Examplefield.text == "test123" {
Label.hidden = false
}
else {
Label.hidden = true
}
}
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
self.view.endEditing(true)
}
func textFieldShouldReturn(textField: UITextField) -> Bool {
self.view.endEditing(true)
return true
}
}
回答by rob mayoff
The simplest solution is probably to connect the “Editing Changed” event of the text field to an action in your view controller:
最简单的解决方案可能是将文本字段的“Editing Changed”事件连接到视图控制器中的操作：
The text field fires the “Editing Changed” event whenever the user changes the contents of the field. You don't have to set the delegate or register for a notification.
每当用户更改字段内容时，文本字段都会触发“Editing Changed”事件。您不必设置委托或注册通知。
There are also “Editing Did End” and “Did End on Exit” events if you want to wait until the user exits the field.
如果您想等到用户退出该字段，还有“Editing Did End”和“Did End on Exit”事件。
回答by Mário Cosme
You need to implement the shouldChangeCharactersInRangemethod from the UITextFieldDelegatein order to check if the string is the same when the text changes:
您需要从UITextFieldDelegate实现shouldChangeCharactersInRange方法，以便在文本更改时检查字符串是否相同：
func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
if (string == "test123") {
self.Label.hidden = false
} else {
self.Label.hidden = true
}
return true
}
回答by g.Rapido
Using shouldChangeCharactersInRangeworks well, but another option would be using the textFieldDidChangeNSNotification.
使用shouldChangeCharactersInRange效果很好，但另一种选择是使用textFieldDidChangeNSNotification。
In your viewDidLoad, register for the notification:
在您的 中viewDidLoad，注册通知：
NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("textFieldDidChange:"), name: "UITextFieldTextDidChangeNotification", object: nil)
Then define the appropriate method:
然后定义合适的方法：
func textFieldDidChange(notification: NSNotification) {
self.label.hidden = (self.textField.text == "test123")
}
回答by prajakta patil
Use UITextField Delegate method
使用 UITextField 委托方法
- (void)textFieldDidBeginEditing:(UITextField *)textField{
// your condition
}
