iOS键盘使用

一、键盘外观设置

UITextField和

UITextView都遵守 UITextInputTraits协议（定义键盘属性），所以可以设置这些对象的属性来设置键盘的外观。

二、键盘通知

UIKeyboardWillShowNotification

UIKeyboardDidShowNotification

UIKeyboardWillHideNotification

UIKeyboardDidHideNotification

通知的userInfo的dic属性中

UIKeyboardFrameBeginUserInfoKey

和

UIKeyboardFrameEndUserInfoKey可以获取到键盘的frame信息。最好使用dic中的frame信息来进行页面适配，因为键盘高度可以变化的。（注意：只使用size不要使用origin，它总是（0，0））

三、调用和关闭

1、使用：[myTextField

becomeFirstResponder

]；

2、关闭：[myTextField

resignFirstResponder];

系统会自动调用键盘，所以一般只需要负责关闭键盘就可以了。

四、键盘遮挡

当键盘遮挡住正在输入的内容，需要进行页面适配，是输入区在键盘上方。比如说在

UITableView或者UIScrollView中有一个输入框，当键盘弹起，你需要做的就是重新设置滚动视图的内容区域，然后滚动所需的文本对象的位置。因此，在UIKeyboardDidShowNotification响应方法中处理以下步骤

得到的键盘的尺寸。

通过调整键盘高度的滚动视图的底部内容插图。

滚动目标文本字段进入可视区域

处理逻辑有2种思路：
1、通过设置内容区域

// Call this method somewhere in your view controller setup code.
- (void)registerForKeyboardNotifications
{
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(keyboardWasShown:)
name:UIKeyboardDidShowNotification object:nil];

[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(keyboardWillBeHidden:)
name:UIKeyboardWillHideNotification object:nil];

}

// Called when the UIKeyboardDidShowNotification is sent.
- (void)keyboardWasShown:(NSNotification*)aNotification
{
NSDictionary* info = [aNotification userInfo];
CGSize kbSize = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;

UIEdgeInsets contentInsets = UIEdgeInsetsMake(0.0, 0.0, kbSize.height, 0.0);
scrollView.contentInset = contentInsets;
scrollView.scrollIndicatorInsets = contentInsets;

// If active text field is hidden by keyboard, scroll it so it's visible
// Your app might not need or want this behavior.
CGRect aRect = self.view.frame;
aRect.size.height -= kbSize.height;
if (!CGRectContainsPoint(aRect, activeField.frame.origin) ) {
[self.scrollView scrollRectToVisible:activeField.frame animated:YES];
}
}

// Called when the UIKeyboardWillHideNotification is sent
- (void)keyboardWillBeHidden:(NSNotification*)aNotification
{
UIEdgeInsets contentInsets = UIEdgeInsetsZero;
scrollView.contentInset = contentInsets;
scrollView.scrollIndicatorInsets = contentInsets;
}

2、设置偏移量

- (void)keyboardWasShown:(NSNotification*)aNotification {
NSDictionary* info = [aNotification userInfo];
CGSize kbSize = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;
CGRect bkgndRect = activeField.superview.frame;
bkgndRect.size.height += kbSize.height;
[activeField.superview setFrame:bkgndRect];
[scrollView setContentOffset:CGPointMake(0.0, activeField.frame.origin.y-kbSize.height) animated:YES];
}

如果该页面有多个输入点，可以通过以下方式获取当前响应的对象

- (void)textFieldDidBeginEditing:(UITextField *)textField
{
activeField = textField;
}

- (void)textFieldDidEndEditing:(UITextField *)textField
{
activeField = nil;
}

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