iPhone: Maintain visibility of form inputs – auto-scrolling views

當(dāng)你開(kāi)發(fā)圖標(biāo)或者任何有輸入?yún)^(qū)域的界面，偶爾輸入框再鍵盤(pán)彈出時(shí)會(huì)被擋住。這樣用戶(hù)體驗(yàn)不好，用戶(hù)在輸入時(shí)看不到他們所輸入的東西。一個(gè)解決方案，是滑動(dòng)整個(gè)view讓編輯區(qū)域一直是可見(jiàn)的。

我提供的整個(gè)解決方案對(duì)UIView添加了一些方法（我知道，添加類(lèi)別到cocoa的類(lèi)是頑皮的）這將決定基于整個(gè)屏幕的輸入位置滑動(dòng)視圖的多少，還有和鍵盤(pán)彈起一樣的速度滑動(dòng)視圖。在編輯完成時(shí)滑動(dòng)回到原來(lái)的位置。

做到這樣很簡(jiǎn)單，這是我如何通過(guò)計(jì)算來(lái)滾動(dòng)視圖：

    - (void) maintainVisibityOfControl:(UIControl *)control offset:(float)offset {
	static const float deviceHeight = 480;
	static const float keyboardHeight = 216;
	static const float gap = 5; //gap between the top of keyboard and the control

	//Find the controls absolute position in the 320*480 window - it could be nested in other views
	CGPoint absolute = [control.superview convertPoint:control.frame.origin toView:nil];

	//If it would be hidden behind the keyboard....
	if (absolute.y > (keyboardHeight + gap)) {
		//Shift the view
		float shiftBy = (deviceHeight - absolute.y) - (deviceHeight - keyboardHeight - gap - offset);
		[UIView beginAnimations:nil context:nil];
		[UIView setAnimationDuration:0.3f]; //this is speed of keyboard
		CGAffineTransform slideTransform = CGAffineTransformMakeTranslation(0.0, shiftBy);
		self.transform = slideTransform;
		[UIView commitAnimations];
	}
}    

    

  

..然后我重置了視圖通過(guò)使用：

    - (void) resetViewToIdentityTransform {
	[UIView beginAnimations:nil context:nil];
	[UIView setAnimationDuration:0.3f]; //this is speed of keyboard
	CGAffineTransform slideTransform = CGAffineTransformIdentity;
	self.transform = slideTransform;
	[UIView commitAnimations];
}    

    

  

你只需要對(duì)你的代碼做一些小的改動(dòng)，并在UITextFieldDelegate調(diào)用這些方法（或其他控制代理）：

    - (void) textFieldDidBeginEditing:(UITextField *)textField {
	[self.view maintainVisibityOfControl:textField offset:0.0f];
}

- (void)textFieldDidEndEditing:(UITextField *)textField {
	if (textField == currentControl) {
		//If the textfield is still the same one, we can reset the view animated
		[self.view resetViewToIdentityTransform];
	}else {
		//However, if the currentControl has changed - that indicates the user has
		//gone into another control - so don't reset view, otherwise animations jump around
	}
}    

    

  

這里是工程拷貝(見(jiàn)我的51CTO博客同名譯文附件)。

iphone:保持表單輸入的可見(jiàn)性——自動(dòng)滾動(dòng)視圖