iphone - Objective-C:UIViewController 中出现的键盘隐藏的 UIScroller 和 UItextfields

Question

我需要帮助尝试在 UIViewController 中配置键盘:(a) 不要悬停在两个 UITextfields 上，因此滚动条应该正确定位； (b) 当用户触摸背景时，键盘消失。

我还没有尝试 (b)，但我正在尝试 (a)，我通过谷歌搜索获得的代码没有给我想要的效果。事实上，当我触摸其中一个文本框时，它会让我的文本框消失。我确定我对 activeField 的实现也是错误的。我从 Apple Development 的键盘部分得到了这个例子。

我目前的代码如下:

@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;
}

Answer 1

我在博客条目中找到了以下代码(我不知道是哪一个，因为我想我在切换到 Google 阅读器同步之前将它保存在 NNW 中)。这一切都存在于实现文件中，只需让您的类成为您的 UITextFields 的委托(delegate)，并在您的 header 中将其声明为遵循 UITextFieldDelegate 协议(protocol)。我直接从我的一个应用程序的代码中提取了这个，它非常适合将文本字段移出键盘。我还没有设置您的 (B)，但我相信这只是另一个需要实现的 UITextFieldDelegate 方法。

为你的类设置以下常量:

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;

然后添加这两个方法:

- (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];
}