我怎么知道UITextField的contentOffset？

Question

我有一个高度为500的UIScrollView，UITextFileds位置为0,100,200,300,400,500（1个UITextFileds，UITextFileds 2,3个UITextFileds，UITextFileds aUITextFileds 4和5）。

ContentOffset位于（0,70）位置。我点击了UITextField 4，我怎么知道TextField 4 contentOffset的位置？

更新

我点击了UITextField 4，我怎么知道我必须上Y像素才能让UITextField不被键盘隐藏？

Answer 1

我的代码：

 - (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.


}

-(void) viewWillAppear: (BOOL) animated {

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWasShown:)  name:UIKeyboardDidShowNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWasHidden:) name:UIKeyboardWillHideNotification object:nil];
}
- (void)singleTapGestureCaptured:(UITapGestureRecognizer *)gesture
{

}


- (void)setScrollView:(UIScrollView *)scrollView offsetToView:(UIView *)view
{

    CGRect contentFrame = CGRectMake(view.frame.origin.x, view.frame.origin.y,view.frame.size.width, view.frame.size.height);
    CGPoint contentOffset = CGPointMake(0, contentFrame.origin.y);

    scrollView.contentOffset = contentOffset;

}


- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField
{
    [self setScrollView:_scrolviewKeys offsetToView:textField];
}

- (void)keyboardWasShown:(NSNotification*)aNotification
{
    NSDictionary* info = [aNotification userInfo];
    CGSize kbSize = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;
    _scrolviewKeys.frame = (CGRect){
        _scrolviewKeys.frame.origin,(CGSize){
                _scrolviewKeys.frame.size.width,_scrolviewKeys.frame.size.height-kbSize.height}


    };
}

点击UITextView黄色

结果：

Answer 2

应该如此简单：

- (void)setScrollView:(UIScrollView *)scrollView bottomOffsetToView:(UIView *)view
{
   scrollView.contentOffset = CGPointMake(0, view.frame.origin.y + view.frame.size.height - 216);
}

然后在您的代码中将自己设置为UITextFieldDelegate并实现：

- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField
{
     self.currentTextField = textField;
}

更新：

你在这里问两个不同的东西..对于键盘通知的键盘寄存器（例如在viewWillAppear中）：

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

然后根据键盘大小更改滚动视图框架：

- (void)keyboardWasShown:(NSNotification*)aNotification
{
    NSDictionary* info = [aNotification userInfo];
    CGSize kbSize = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;
    self.scrollView.frame = (CGRect){self.scrollView.frame.origin,(CGSize){self.scrollView.frame.size.width,self.scrollView.frame.size.height-kbSize.height);
    if (self.currentTextField != nil)
    {
        [self setScrollView:self.scrollView bottomOffsetToView:self.currentTextField];
    }
}

与KeyboardWasHidden相同的行为（重置初始帧）并且不要忘记在viewDidDisappear中删除Observer。

Answer 3

在iOS 7中，scrollView将自动滚动最小量以保持textField可见。如果你使用的是iOS 6，那么你可以做的就是模仿同样的行为。

假设您在键盘显示如下后调整了scrollView.contentInset，这就是我在- (void)textFieldDidBeginEditing:(UITextField *)textField中所做的：

self.scrollView.contentInset = (UIEdgeInsets){.bottom = 216.0f};
self.scrollView.scrollIndicatorInsets = self.scrollView.contentInset;

CGFloat minY = CGRectGetMinY([self.view convertRect:textField.frame fromView:textField]);
if (minY > self.scrollView.contentInset.bottom) {
    CGFloat visibleHeight = CGRectGetHeight(self.scrollView.bounds) - self.scrollView.contentInset.bottom;
    [self.scrollView setContentOffset:CGPointMake(0.0f, CGRectGetMaxY([self.view convertRect:textField.frame fromView:textField]) - visibleHeight) animated:YES];
}

我们首先在参考scrollView的框架时计算textField的框架的minY，然后查看它是否大于我们插入scrollView的数量。如果是，那意味着scrollView的这一部分现在在键盘下面。然后我们通过考虑visibleHeight来计算偏移量，这是显示键盘后scrollView的可见内容。取textField的框架的maxY并减去visibleHeight以使其与键盘的顶部对齐，从而将scrollView移动到最小量以使其保持可见。