在点击键盘上方移动文本字段的逻辑

Question

现在，我有一些基本代码可以在您开始编辑时移动键盘上方的文本字段。但是，文本字段的大小因设备和方向而异。所以，我写了一个粗略的方法，它不会一直保持在键盘上方，而是在你旋转它时会进一步上升，所以它看起来不像我想要的那样专业。

我的问题的基本意义是，是否有一种逻辑可以根据设备和方向获取键盘的大小，并自动使用该值，希望比这更快。

如果这是最好的方法，请告诉我。否则，请提供输入。这是我拥有的代码。 （这里只是上移代码，不是下移代码，以免占用太多空间）

- (void)textFieldDidBeginEditing:(UITextField *)textField { 

    //Get Device Type
    NSString *deviceType = [[UIDevice currentDevice] model];

    //Animate Text Field
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDelegate:self];
    [UIView setAnimationDuration:0.4];
    [UIView setAnimationBeginsFromCurrentState:YES];

    if ([deviceType isEqualToString:@"iPhone"]) {

        //Size For iPhone
        googleBar.frame = CGRectMake(googleBar.frame.origin.x - 62.0, (googleBar.frame.origin.y - 210.0), googleBar.frame.size.width + 120.0, googleBar.frame.size.height);

    } else if ([deviceType isEqualToString:@"iPad"]) {

        //Size for iPad
        googleBar.frame = CGRectMake(googleBar.frame.origin.x - 62.0, (googleBar.frame.origin.y - 320.0), googleBar.frame.size.width + 120.0, googleBar.frame.size.height);

    } else if ([deviceType isEqualToString:@"iPod touch"]) {

        //Size For iPod Touch
        googleBar.frame = CGRectMake(googleBar.frame.origin.x - 62.0, (googleBar.frame.origin.y - 210.0), googleBar.frame.size.width + 120.0, googleBar.frame.size.height);

    } 

    [UIView commitAnimations];

} 

Answer 1

你真正想做的是观察 UIKeyboard(Did|Will)(Show|Hide) 通知。它们在其 userInfo 字典中包含开始和结束帧，以及正确的动画曲线和持续时间。

因此，在观察此通知后，根据提供的动画提示，当它发布时，根据通知中传递的帧的大小移动您的文本字段。

您可以在 UIWindow 类参考的“通知”部分查看更多信息：https://developer.apple.com/library/ios/#documentation/uikit/reference/UIWindow_Class/UIWindowClassReference/UIWindowClassReference.html

下面是一个示例视图控制器实现。这个视图控制器的 nib 只是一个单独的文本字段，它连接了一个插座，并且文本字段的委托设置为视图控制器。

@interface ViewController ()

- (void)viewControllerInit;

@end

@implementation ViewController

@synthesize textField;

- (id)initWithCoder:(NSCoder *)coder {
    self = [super initWithCoder:coder];
    if (self) {
        [self viewControllerInit];
    }
    return self;
}

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil])
    {
        [self viewControllerInit];
    }
    return self;
}


- (void)viewControllerInit
{
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];
}


- (void)dealloc {
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}


#pragma mark - Notification Handlers

- (void)keyboardWillShow:(NSNotification *)notification
{
    // I'll try to make my text field 20 pixels above the top of the keyboard
    // To do this first we need to find out where the keyboard will be.

    NSValue *keyboardEndFrameValue = [[notification userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey];
    CGRect keyboardEndFrame = [keyboardEndFrameValue CGRectValue];

    // When we move the textField up, we want to match the animation duration and curve that
    // the keyboard displays. So we get those values out now

    NSNumber *animationDurationNumber = [[notification userInfo] objectForKey:UIKeyboardAnimationDurationUserInfoKey];
    NSTimeInterval animationDuration = [animationDurationNumber doubleValue];

    NSNumber *animationCurveNumber = [[notification userInfo] objectForKey:UIKeyboardAnimationCurveUserInfoKey];
    UIViewAnimationCurve animationCurve = [animationCurveNumber intValue];

    // UIView's block-based animation methods anticipate not a UIVieAnimationCurve but a UIViewAnimationOptions.
    // We shift it according to the docs to get this curve.

    UIViewAnimationOptions animationOptions = animationCurve << 16;


    // Now we set up our animation block.
    [UIView animateWithDuration:animationDuration 
                          delay:0.0 
                        options:animationOptions 
                     animations:^{
                         // Now we just animate the text field up an amount according to the keyboard's height,
                         // as we mentioned above.
                        CGRect textFieldFrame = self.textField.frame;
                        textFieldFrame.origin.y = keyboardEndFrame.origin.y - textFieldFrame.size.height - 40; //I don't think the keyboard takes into account the status bar
                        self.textField.frame = textFieldFrame;
                     } 
                     completion:^(BOOL finished) {}];

}


- (void)keyboardWillHide:(NSNotification *)notification
{

    NSNumber *animationDurationNumber = [[notification userInfo] objectForKey:UIKeyboardAnimationDurationUserInfoKey];
    NSTimeInterval animationDuration = [animationDurationNumber doubleValue];

    NSNumber *animationCurveNumber = [[notification userInfo] objectForKey:UIKeyboardAnimationCurveUserInfoKey];
    UIViewAnimationCurve animationCurve = [animationCurveNumber intValue];
    UIViewAnimationOptions animationOptions = animationCurve << 16;

    [UIView animateWithDuration:animationDuration 
                          delay:0.0 
                        options:animationOptions 
                     animations:^{
                         self.textField.frame = CGRectMake(20, 409, 280, 31); //just some hard coded value
                     } 
                     completion:^(BOOL finished) {}];

}
#pragma mark - View lifecycle

- (void)viewDidUnload
{
    [self setTextField:nil];
    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}

#pragma mark - UITextFieldDelegate

- (BOOL)textFieldShouldReturn:(UITextField *)textField
{
    [self.textField resignFirstResponder];
    return YES;
}

@end

Answer 2

使用通知键盘寄存器，您可以将您的文本字段放在滚动中并管理滚动的内容偏移量，以便在必要时将实际的第一响应者置于键盘上方。

所以在注册控制器到键盘出现后，你必须获取键盘原点和滚动原点相对于父级的距离。

您必须知道特定的第一响应者是否可以更改滚动的内容偏移量，因此有必要知道键盘原点和第一响应者之间可能存在的界限。

顺便说一句，您需要知道滚动内容偏移量和第一响应者之间的差距，以便将您的第一响应者放置在特定位置。

@interface MainViewController : UIViewController

  @property (strong, nonatomic) IBOutlet UIScrollView *scroll;

@end    

@interface MainViewController ()
{
   CGPoint scrollOffset;
}
@end 

@implementation MainViewController

@synthesize scroll

-(void)viewWillAppear:(BOOL)animated
 {
    [[ NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillAppear:) name:UIKeyboardDidShowNotification object:nil];

    [[ NSNotificationCenter defaultCenter ] addObserver:self selector:@selector(keyboardWillDisAppear:) name:UIKeyboardDidHideNotification object:nil];

 }


-(void)viewWillDisappear:(BOOL)animated
 {
    [[ NSNotificationCenter defaultCenter ] removeObserver:self ];
 }

-(void)keyboardWillAppear:(NSNotification*) note
 {
   const CGFloat default_gap = 25.0f;

   NSValue *keyBoardEndFrameValue = [[ note userInfo ] objectForKey:UIKeyboardFrameEndUserInfoKey ];

   CGRect keyBoardFrame = [ keyBoardEndFrameValue CGRectValue ];


   offset = scroll.contentOffset;

   UIWindow *window = [[ UIApplication sharedApplication ] keyWindow];
   UITextField *textField = (UITextField*)[ window performSelector:@selector(firstResponder) ];

   //Gap between keyboard origin and the scroll origin, relative to parent.
   CGFloat distanceRelativeToParent = keyBoardFrame.origin.y - scroll.frame.origin.y; 


   //Distance between superview to textfield inside scroll. to determine if it's necesary to scroll.
   CGFloat bound = (textField.frame.origin.y + textField.frame.size.height)+scroll.frame.origin.y; 

   CGFloat gapScroll = textField.frame.size.height+default_gap;

  if( bound >= keyBoardFrame.origin.y )
   {
     [ UIView animateWithDuration:.3 delay:0.0 options:UIViewAnimationCurveEaseOut 
   animations:^{

        [ scroll setContentOffset:CGPointMake(0, textField.frame.origin.y - distanceRelativeToParent +  gapScroll  ) animated:YES ];

   }
  completion:^(BOOL finished){

   }];
}

}

-(void) keyboardWillDisAppear:(NSNotification*) note
{   
   [ scroll setContentOffset:offset animated:YES ];
}
@end

Answer 3

UIViewControllers 有一个名为 interfaceOrientation 的属性和 UIInterfaceOrientationIsPortrait/Landscape 函数，所以基本上你可以这样做：

if(UIInterfaceOrientationIsPortrait(self.interfaceOrientation){
//portrait logic
}
else{
//landcapeLogic
}

在您的视图控制器中为每个 iPhone 和 iPad。从那里您可以像以前一样进行像素测量，因为据我所知，这是最简单的方法。

附：也有一个检查横向检查器的功能，但是如果第一个 if 语句是 false 意味着设备不是纵向的，那么它必须是横向的，因此是普通的 else。