检测开始和停止编辑 UITextView

Question

如何在进入 UITextView（用户点击编辑它）并离开视图（用户点击离开它）时调用一些代码？

感谢任何帮助。

Answer 1

http://developer.apple.com/library/ios/#documentation/uikit/reference/UITextViewDelegate_Protocol/Reference/UITextViewDelegate.html#//apple_ref/occ/intf/UITextViewDelegate

您可以在这里找到几种有用的调查方法：

• textViewDidBeginEditing:
• textViewDidEndEditing:

此外，要离开UITextView，您通常应该执行调用[yourTextView resignFirstResponder];的操作

Objective-C 示例

//you may specify UITextViewDelegate protocol in .h file interface, but it's better not to expose it if not necessary
@interface ExampleViewController()<UITextViewDelegate> 

@end

@implementation ExampleViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    //assuming _textView is already instantiated and added to its superview
    _textView.delegate = self;
}


//it's nice to separate delegate methods with pragmas but it's up to your local code style policy
#pragma mark UITextViewDelegate

- (void)textViewDidBeginEditing:(UITextView *)textView {
    //handle user taps text view to type text
}

- (void)textViewDidEndEditing:(UITextView *)textView {
    //handle text editing finished    
}

@end

Swift 示例

class TextViewEventsViewController: UIViewController, UITextViewDelegate {
    
    @IBOutlet weak var exampleTextView: UITextView!

    override func viewDidLoad() {
        super.viewDidLoad()
        
        self.exampleTextView.delegate = self
    }
    
    func textViewDidBeginEditing(_ textView: UITextView) {
        print("exampleTextView: BEGIN EDIT")
    }
    
    func textViewDidEndEditing(_ textView: UITextView) {
        print("exampleTextView: END EDIT")
    }
}

Answer 2

您还可以实现 UITextViewDidChange 委托方法。我在我的应用程序中使用下面的代码来快速记笔记。每当用户输入一个字符时，观察者就会从通知中心捕捉到它并调用 saveText 方法。

方法如下：

将此行添加到 viewDidLoad 方法：

[NSNotificationCenter.defaultCenter addObserver:self selector:@selector(textViewDidChange:) name:UITextViewTextDidChangeNotification object:nil];

这些行位于代码中的适当位置（例如处理文本视图委托方法的部分。提示：为此使用编译指示标记（#pragma mark - TextView 委托方法）：

- (void)textViewDidChange:(UITextView *)textView{

    NSLog(@"textViewShouldEndEditing"); // Detect in log output if the method gets called
    [self saveText:nil]; // Call any method you like

}

Answer 3

使用委托并使用：

- (void) textViewDidBeginEditing:(UITextView *) textView {
    // Your code here
}

Answer 4

txtviewaddress.text="Address"

txtViewAddress.TextColor = UIColor.LightGray;
txtViewAddress.ShouldBeginEditing += (textView) =>
        {
 txtViewAddress.Text = "";
            txtViewAddress.TextColor = UIColor.Black;
            return true;
};
txtViewAddress.ShouldEndEditing += (textView) =>
        {
            if (textView.Text == "")
            {
                txtViewAddress.Text = " Address";
                txtViewAddress.TextColor = UIColor.LightGray;

            }
            return true;
        };