Objective-C:UIViewController中出现了被键盘隐藏的UIScroller和UItextfields

问题描述

我需要帮助来尝试在UIViewController中配置键盘:(a)不要将鼠标悬停在两个UITextfield上，因此滚动条应正确放置； (b)当用户触摸背景时，键盘消失.

I need help trying to configure in a UIViewController, the keyboard : (a) not hovering over both UITextfields, so the scroller should be positioned correctly; and (b) When the user touches the background the keyboard disappears.

我还没有尝试过(b)，但是我正在尝试(a)，我从谷歌搜索中获得的代码没有给我想要的效果.实际上，当我触摸其中的一个文本框时，它会消失.我确定我的activeField的实现也是错误的.我从Apple Development的Keyboard部分获得了这个示例.

I haven't tried (b) yet but I'm trying (a) and the code I got from googling around didn't give me the desired effects. In-fact, it makes my textboxes disappear when I touch one of them. Im sure my implementation of activeField is also wrong. I got this example from Apple Development's Keyboard section.

@interface FirstViewController : UIViewController {
    IBOutlet UITextField *emailAddress;
    IBOutlet UITextField *password;
    IBOutlet UIButton *loginButton;
    IBOutlet UIScrollView *scroller;
    BOOL keyboardShown;
    UITextField *activeField;

    ASIHTTPRequest *requestRequiringAuthentication;
    ASINetworkQueue *networkQueue;
}

- (IBAction) LoginUser:(id)sender;

@property (nonatomic,retain) IBOutlet UITextField *emailAddress;
@property (nonatomic,retain) IBOutlet UITextField *password;
@property (nonatomic, retain) IBOutlet UIScrollView *scroller;
@property (nonatomic, retain) UITextField *activeField;
@property (retain) ASINetworkQueue *networkQueue;
@property (retain) ASIHTTPRequest *requestRequiringAuthentication;

@end


@implementation FirstViewController

@synthesize requestRequiringAuthentication;
@synthesize networkQueue;
@synthesize password;
@synthesize emailAddress;
@synthesize scroller;
@synthesize activeField;

#pragma mark -
#pragma mark LifeCycle

- (void)awakeFromNib
{
    NSLog(@"awaking from nib");
    [self setNetworkQueue:[[[ASINetworkQueue alloc] init] autorelease]];
}

- (void)viewDidLoad {
    NSLog(@"viewdidload");
    [super viewDidLoad];
}

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

- (void)viewWillAppear:(BOOL)animated {
    keyboardShown = NO;
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWasShown:) name:UIKeyboardDidShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWasHidden:) name:UIKeyboardDidHideNotification object:nil];
[super viewWillAppear:animated];
}

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


// Called when the UIKeyboardDidShowNotification is sent.
- (void)keyboardWasShown:(NSNotification*)aNotification
{
    if (keyboardShown)
        return;

    NSDictionary* info = [aNotification userInfo];

    // Get the size of the keyboard.
    NSValue* aValue = [info objectForKey:UIKeyboardBoundsUserInfoKey];
    CGSize keyboardSize = [aValue CGRectValue].size;

    // Resize the scroll view (which is the root view of the window)
    CGRect viewFrame = [scroller frame];
    viewFrame.size.height -= keyboardSize.height;
    scroller.frame = viewFrame;

    // Scroll the active text field into view.
    CGRect textFieldRect = [activeField frame];
    [scroller scrollRectToVisible:textFieldRect animated:YES];

    keyboardShown = YES;
}

// Called when the UIKeyboardDidHideNotification is sent
- (void)keyboardWasHidden:(NSNotification*)aNotification
{
    NSDictionary* info = [aNotification userInfo];

    // Get the size of the keyboard.
    NSValue* aValue = [info objectForKey:UIKeyboardBoundsUserInfoKey];
    CGSize keyboardSize = [aValue CGRectValue].size;

    // Reset the height of the scroll view to its original value
    CGRect viewFrame = [scroller frame];
    viewFrame.size.height += keyboardSize.height;
    scroller.frame = viewFrame;

    keyboardShown = NO;
}

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

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

推荐答案

我在博客条目中找到了以下代码(我不知道是哪一个，因为我认为在切换至Google Reader同步之前我已将其保存在NNW中).它全部存在于实现文件中，只需将您的类作为UITextField的委托，然后将其声明为遵循标题中的UITextFieldDelegate协议即可.我直接从其中一个运输应用程序的代码中删除了此代码，它非常适合将文本字段移出键盘.我尚未设置您的(B)，但我相信这只是需要实现的另一个UITextFieldDelegate方法.

I found the following code in a blog entry (I don't know which one because I think I had it saved in NNW before the switch to Google Reader syncing). It all lives in the implementation file, just make your class the delegate for your UITextFields, and declare it as following the UITextFieldDelegate protocol in your header. I pulled this straight out of the code for one of my shipping apps, and it works great for moving the text fields out of the way of the keyboard. I haven't setup your (B) yet, but I believe it's just another UITextFieldDelegate method that needs to be implemented.

为您的课程设置以下常量:

Setup the following constants for your class:

static const CGFloat KEYBOARD_ANIMATION_DURATION = 0.3;
static const CGFloat MINIMUM_SCROLL_FRACTION = 0.2;
static const CGFloat MAXIMUM_SCROLL_FRACTION = 0.8;
static const CGFloat PORTRAIT_KEYBOARD_HEIGHT = 216;
static const CGFloat LANDSCAPE_KEYBOARD_HEIGHT = 140;

然后添加以下两种方法:

And then add these two methods:

- (void)textFieldDidBeginEditing:(UITextField *)textField {
   CGRect textFieldRect = [self.view.window convertRect:textField.bounds fromView:textField];
    CGRect viewRect = [self.view.window convertRect:self.view.bounds fromView:self.view];

    CGFloat midline = textFieldRect.origin.y + 0.5 * textFieldRect.size.height;
    CGFloat numerator =
            midline - viewRect.origin.y - MINIMUM_SCROLL_FRACTION * viewRect.size.height;
    CGFloat denominator =
            (MAXIMUM_SCROLL_FRACTION - MINIMUM_SCROLL_FRACTION) * viewRect.size.height;
    CGFloat heightFraction = numerator / denominator;

   if (heightFraction < 0.0)
    {
        heightFraction = 0.0;
    }
    else if (heightFraction > 1.0)
    {
        heightFraction = 1.0;
    }

   UIInterfaceOrientation orientation =
   [[UIApplication sharedApplication] statusBarOrientation];
    if (orientation == UIInterfaceOrientationPortrait ||
        orientation == UIInterfaceOrientationPortraitUpsideDown)
    {
        animatedDistance = floor(PORTRAIT_KEYBOARD_HEIGHT * heightFraction);
    }
    else
    {
        animatedDistance = floor(LANDSCAPE_KEYBOARD_HEIGHT * heightFraction);
    }
    CGFloat heightFraction = numerator / denominator;

   if (heightFraction < 0.0)
    {
        heightFraction = 0.0;
    }
    else if (heightFraction > 1.0)
    {
        heightFraction = 1.0;
    }

   UIInterfaceOrientation orientation =
   [[UIApplication sharedApplication] statusBarOrientation];
    if (orientation == UIInterfaceOrientationPortrait ||
        orientation == UIInterfaceOrientationPortraitUpsideDown)
    {
        animatedDistance = floor(PORTRAIT_KEYBOARD_HEIGHT * heightFraction);
    }
    else
    {
        animatedDistance = floor(LANDSCAPE_KEYBOARD_HEIGHT * heightFraction);
    }

   CGRect viewFrame = self.view.frame;
    viewFrame.origin.y -= animatedDistance;

    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationBeginsFromCurrentState:YES];
    [UIView setAnimationDuration:KEYBOARD_ANIMATION_DURATION];

    [self.view setFrame:viewFrame];

    [UIView commitAnimations];
}

- (void)textFieldDidEndEditing:(UITextField *)textField {
    CGRect viewFrame = self.view.frame;
    viewFrame.origin.y += animatedDistance;

    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationBeginsFromCurrentState:YES];
    [UIView setAnimationDuration:KEYBOARD_ANIMATION_DURATION];

    [self.view setFrame:viewFrame];

    [UIView commitAnimations];
}

这篇关于Objective-C:UIViewController中出现了被键盘隐藏的UIScroller和UItextfields的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！