避免弹出键盘遮盖住视图上的控件代码,ObjC代码库,德仔网

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【ObjC】避免弹出键盘遮盖住视图上的控件

作者:万鑫 / 发布于2014/11/15/ 455

当需要输入文字时，弹出的键盘通常会将需要输入文字的UITextField遮盖住。这段代码利用scrollview来解决这个问题。


	// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
	- (void)viewDidLoad
	{
	 [super viewDidLoad];
	
	 // register for keyboard notifications
	 [[NSNotificationCenter defaultCenter] addObserver:self
	 selector:@selector(keyboardWillShow:）
	 name:UIKeyboardWillShowNotification
	 object:self.view.window];
	 // register for keyboard notifications
	 [[NSNotificationCenter defaultCenter] addObserver:self
	 selector:@selector(keyboardWillHide:)
	 name:UIKeyboardWillHideNotification
	 object:self.view.window];
	 keyboardIsShown = NO;
	 //make contentSize bigger than your scrollSize
	 //(you will need to figure out for your own use case)
	 CGSize scrollContentSize = CGSizeMake(320, 345);
	 self.scrollView.contentSize = scrollContentSize;
	}
	
	- (void)viewDidUnload {
	 // Release any retained subviews of the main view.
	 // e.g. self.myOutlet = nil;
	
	 // unregister for keyboard notifications while not visible.
	 [[NSNotificationCenter defaultCenter] removeObserver:self
	 name:UIKeyboardWillShowNotification
	 object:nil];
	 // unregister for keyboard notifications while not visible.
	 [[NSNotificationCenter defaultCenter] removeObserver:self
	 name:UIKeyboardWillHideNotification
	 object:nil];
	}
	
	- (void)dealloc {
	 // Release any retained subviews of the main view.
	 // e.g. self.myOutlet = nil;
	
	 // unregister for keyboard notifications while not visible.
	 [[NSNotificationCenter defaultCenter] removeObserver:self
	 name:UIKeyboardWillShowNotification
	 object:nil];
	 // unregister for keyboard notifications while not visible.
	 [[NSNotificationCenter defaultCenter] removeObserver:self
	 name:UIKeyboardWillHideNotification
	 object:nil];
	}
	
	- (void)keyboardWillHide:(NSNotification *)n
	{
	 NSDictionary* userInfo = [n userInfo];
	 // get the size of the keyboard
	 CGSize keyboardSize =
	 [[userInfo objectForKey:UIKeyboardFrameBeginUserInfoKey]
	 CGRectValue].size;
	 // resize the scrollview
	 CGRect viewFrame = self.scrollView.frame;
	 // I'm also subtracting a constant kTabBarHeight because my UIScrollView
	 // was offset by the UITabBar so really only the portion of the keyboard that
	 // is leftover pass the UITabBar is obscuring my UIScrollView.
	 viewFrame.size.height += (keyboardSize.height - kTabBarHeight);
	 [UIView beginAnimations:nil context:NULL];
	 [UIView setAnimationBeginsFromCurrentState:YES];
	 // The kKeyboardAnimationDuration I am using is 0.3
	 [UIView setAnimationDuration:kKeyboardAnimationDuration];
	 [self.scrollView setFrame:viewFrame];
	 [UIView commitAnimations];
	 keyboardIsShown = NO;
	}
	
	- (void)keyboardWillShow:(NSNotification *)n
	{
	 // This is an ivar I'm using to ensure that we do not do the frame size
	 // adjustment on the UIScrollView if the keyboard is already shown.
	 // This can happen if the user, after fixing editing a UITextField,
	 // scrolls the resized UIScrollView to another UITextField and attempts
	 // to edit the next UITextField. If we were to resize the UIScrollView again,
	 // it would be disastrous. NOTE: The keyboard notification will fire
	 // even when the keyboard is already shown.
	 if (keyboardIsShown) {
	 return;
	 }
	
	 NSDictionary* userInfo = [n userInfo];
	
	 // get the size of the keyboard
	 CGSize keyboardSize =
	 [[userInfo objectForKey:UIKeyboardFrameBeginUserInfoKey]
	 CGRectValue].size;
	
	 // resize the noteView
	 CGRect viewFrame = self.scrollView.frame;
	 // I'm also subtracting a constant kTabBarHeight because my UIScrollView
	 // was offset by the UITabBar so really only the portion of the keyboard
	 // that is leftover pass the UITabBar is obscuring my UIScrollView.
	 viewFrame.size.height -= (keyboardSize.height - kTabBarHeight);
	 [UIView beginAnimations:nil context:NULL];
	 [UIView setAnimationBeginsFromCurrentState:YES];
	 // The kKeyboardAnimationDuration I am using is 0.3
	 [UIView setAnimationDuration:kKeyboardAnimationDuration];
	 [self.scrollView setFrame:viewFrame];
	 [UIView commitAnimations];
	 keyboardIsShown = YES;
	}

试试其它关键字

　视图上　　 scrollview　

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