iOS 解決表單被鍵盤遮住的問題


問題

處理表單的時候,一定會碰到的就是輸入控件被鍵盤遮住的問題,如圖:

實例實例

左邊是普通表單,中間是2B表單,右邊是文藝表單.

分析

處理這種問題無非就是2個步驟:

  1. 鍵盤彈出時,縮小UITableViewframe
  2. 滾動UITableView,讓當前輸入的控件可見

代碼寫出來就是這幾步

  1. 捕獲鍵盤事件
  2. 計算鍵盤高度並調整UITableViewframe
  3. 獲取當前正在輸入的控件
  4. 計算其在UITableView中的位置,並滾動到其位置讓其可見

那么如何一步一步的來實現這些步驟呢?

捕獲鍵盤事件

捕獲鍵盤事件

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

- (void)actionKeyboardShow:(NSNotification *)notification
{
[[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardDidShowNotification object:nil];
[[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardDidChangeFrameNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(actionKeyboardShow:)
name:UIKeyboardDidChangeFrameNotification
object:nil];

}

- (void)actionKeyboardHide:(NSNotification *)notification
{
[[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardDidChangeFrameNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(actionKeyboardShow:)
name:UIKeyboardDidShowNotification
object:nil];
}

計算鍵盤高度並調整UITableViewframe

計算鍵盤高度並調整UITableView的frame

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- (void)actionKeyboardShow:(NSNotification *)notification
{
CGSize keyboardSize = [[[notification userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue].size
self.tableView.frame = CGRectMake(0, 0, 320, self.view.h-keyboardSize.height);

[[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardDidShowNotification object:nil];
[[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardDidChangeFrameNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(actionKeyboardShow:)
name:UIKeyboardDidChangeFrameNotification
object:nil];

}

獲取當前正在輸入的控件

這里得說一句,普通程序員一般是這樣來獲取的

UIView的Category

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- (UIView *) getFirstResponder
{
if (self.isFirstResponder) {
return self;
}

for (UIView *subView in self.subviews) {
UIView *firstResponder = [subView getFirstResponder];
if (firstResponder != nil) {
return firstResponder;
}
}

return nil;
}

雖然沒錯,但是文藝程序員應該這樣來獲取

UIResponder的Category

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static __weak id currentFirstResponder;

+(id)currentFirstResponder {
currentFirstResponder = nil;
[[UIApplication sharedApplication] sendAction:@selector(findFirstResponder:) to:nil from:nil forEvent:nil];
return currentFirstResponder;
}

-(void)findFirstResponder:(id)sender {
currentFirstResponder = self;
}

同理,有時候我們需要讓鍵盤消失,那么也有三種做法可以選擇

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[someView resignFirstResponder];

[self.view endEditing:YES];

[[UIApplication sharedApplication] sendAction:@selector(resignFirstResponder) to:nil from:nil forEvent:nil];

如何選擇呢? It’s up to U.

計算其在UITableView中的位置,並滾動到其位置讓其可見

計算其在UITableView中的位置,並滾動到其位置讓其可見

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- (void)actionKeyboardShow:(NSNotification *)notification
{
CGSize keyboardSize = [[[notification userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue].size;
self.tableView.frame = CGRectMake(0, 0, 320, self.view.h-keyboardSize.height);

UIView *v = [UIResponder currentFirstResponder];

if ( v )
{
while ( ![v isKindOfClass:[UITableViewCell class]]) {
v = v.superview;
}

UITableViewCell *cell = (UITableViewCell*)v;

[self.tableView scrollToRowAtIndexPath:[self.tableView indexPathForRowAtPoint:cell.center] atScrollPosition:UITableViewScrollPositionBottom animated:YES];
}

[[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardDidShowNotification object:nil];
[[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardDidChangeFrameNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(actionKeyboardShow:)
name:UIKeyboardDidChangeFrameNotification
object:nil];

}

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