Monotouch 移动位于键盘下的内容，自动滚动被键盘遮住的内容
IOS官方的Object-C有例子，但是OC的代码。Moving Content That Is Located Under the Keyboard
效果如下图：
实现方法：
1.定义一个所有ViewControl的基类，命名为ViewControllerBase，ViewControl继承ViewControllerBase
代码如下：
1: public class ViewControllerBase : UIViewController
2: {
3: NSObject _keyboardObserverWillShow;
4: NSObject _keyboardObserverWillHide;
5:
6: public ViewControllerBase()
7: {
8: }
9: public ViewControllerBase(IntPtr handle) : base(handle)
10: {
11:
12: }
13:
14: public override void ViewDidLoad()
15: {
16: //设置键盘事件处理程序
17: RegisterForKeyboardNotifications();
18: }
19:
20: protected virtual void RegisterForKeyboardNotifications()
21: {
22: _keyboardObserverWillShow = NSNotificationCenter.DefaultCenter.AddObserver
23: (UIKeyboard.WillShowNotification, KeyboardWillShowNotification);
24:
25: _keyboardObserverWillHide = NSNotificationCenter.DefaultCenter.AddObserver
26: (UIKeyboard.WillHideNotification, KeyboardWillHideNotification);
27: }
28:
29: protected virtual void UnregisterKeyboardNotifications()
30: {
31: NSNotificationCenter.DefaultCenter.RemoveObserver(_keyboardObserverWillShow);
32: NSNotificationCenter.DefaultCenter.RemoveObserver(_keyboardObserverWillHide);
33: }
34:
35: protected virtual UIView KeyboardGetActiveView()
36: {
37: return this.View.FindFirstResponder();
38: }
39:
40: protected virtual void KeyboardWillShowNotification(NSNotification notification)
41: {
42: UIView activeView = KeyboardGetActiveView();
43: if (activeView == null)
44: return;
45:
46: UIScrollView scrollView = activeView.FindSuperviewOfType(this.View, typeof(UIScrollView)) as UIScrollView;
47: if (scrollView == null)
48: return;
49:
50: RectangleF keyboardBounds = UIKeyboard.BoundsFromNotification(notification);
51:
52: UIEdgeInsets contentInsets = new UIEdgeInsets(0.0f, 0.0f, keyboardBounds.Size.Height, 0.0f);
53: scrollView.ContentInset = contentInsets;
54: scrollView.ScrollIndicatorInsets = contentInsets;
55:
56: RectangleF viewRectAboveKeyboard = new RectangleF(this.View.Frame.Location,
57: new SizeF(this.View.Frame.Width, this.View.Frame.Size.Height - keyboardBounds.Size.Height));
58:
59: RectangleF activeFieldAbsoluteFrame = activeView.Superview.ConvertRectToView(activeView.Frame, this.View);
60:
61: if (!viewRectAboveKeyboard.Contains(activeFieldAbsoluteFrame))
62: {
63: PointF scrollPoint = new PointF(0.0f,
64: activeFieldAbsoluteFrame.Location.Y + activeFieldAbsoluteFrame.Height
65: + scrollView.ContentOffset.Y - viewRectAboveKeyboard.Height);
66: scrollView.SetContentOffset(scrollPoint, true);
67: }
68: }
69:
70: protected virtual void KeyboardWillHideNotification(NSNotification notification)
71: {
72: UIView activeView = KeyboardGetActiveView();
73: if (activeView == null)
74: return;
75:
76: UIScrollView scrollView = activeView.FindSuperviewOfType(this.View, typeof(UIScrollView)) as UIScrollView;
77: if (scrollView == null)
78: return;
79:
80: double animationDuration = UIKeyboard.AnimationDurationFromNotification(notification);
81: UIEdgeInsets contentInsets = new UIEdgeInsets(0.0f, 0.0f, 0.0f, 0.0f);
82: UIView.Animate(animationDuration, delegate
83: {
84: scrollView.ContentInset = contentInsets;
85: scrollView.ScrollIndicatorInsets = contentInsets;
86: });
87: }
88: }
代码如下：
1: public static class ViewExtensions
2: {
3: public static UIView FindFirstResponder(this UIView view)
4: {
5: if (view.IsFirstResponder)
6: {
7: return view;
8: }
9: foreach (UIView subView in view.Subviews)
10: {
11: var firstResponder = subView.FindFirstResponder();
12: if (firstResponder != null)
13: return firstResponder;
14: }
15: return null;
16: }
17:
18: public static UIView FindSuperviewOfType(this UIView view, UIView stopAt, Type type)
19: {
20: if (view.Superview != null)
21: {
22: if (type.IsAssignableFrom(view.Superview.GetType()))
23: {
24: return view.Superview;
25: }
26:
27: if (view.Superview != stopAt)
28: return view.Superview.FindSuperviewOfType(stopAt, type);
29: }
30:
31: return null;
32: }
33: }
实现的效果：
作者：Bruce Lee
出处：http://www.cnblogs.com/BruceLee521
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