Keyboard and getting up state on iPhone

How do I find out if the keyboard is up?

I have a UISearchbar instance which becomes the first responder.

When the keyboard appears a notification is sent out as part of the API, however I don't want t开发者_JAVA技巧o respond to this right away. I could record this in a boolean state, but that seems clunky. I'd like to know if there is a "getter" some where I can call to find out.

This is how I do it:

KeyboardStateListener.h

@interface KeyboardStateListener : NSObject {
    BOOL _isVisible;
}
+ (KeyboardStateListener *) sharedInstance;
@property (nonatomic, readonly, getter=isVisible) BOOL visible;
@end

KeyboardStateListener.m

#import "KeyboardStateListener.h"

static KeyboardStateListener *sharedObj;

@implementation KeyboardStateListener

+ (KeyboardStateListener *)sharedInstance
{
    return sharedObj;
}
+ (void)load
{
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
    sharedObj = [[self alloc] init];
    [pool release];
}
- (BOOL)isVisible
{
    return _isVisible;
}
- (void)didShow
{
    _isVisible = YES;
}
- (void)didHide
{
    _isVisible = NO;
}
- (id)init
{
    if ((self = [super init])) {
        NSNotificationCenter *center = [NSNotificationCenter defaultCenter];
        [center addObserver:self selector:@selector(didShow) name:UIKeyboardDidShowNotification object:nil];
        [center addObserver:self selector:@selector(didHide) name:UIKeyboardWillHideNotification object:nil];
    }
    return self;
}

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

@end

Then use this to figure out the rest:

KeyboardStateListener *obj = [KeyboardStateListener sharedInstance];
if ([obj isVisible]) {
    //Keyboard is up
}

The only sure way that I can think to do it as you said. using notifications like this:

[[NSNotificationCenter defaultCenter] addObserver:self 
                                         selector:@selector(keyboardWillShow:) 
                                             name:UIKeyboardWillShowNotification 
                                           object:nil];

and then

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

Other than that, you may be able to iterate through your views subviews and look for the keyboard like:

UIView *keyboard = nil;

for (UIView *potentialKeyboard in [myWindow subviews]) {

    // iOS 4
    if ([[potentialKeyboard description] hasPrefix:@"<UIPeripheralHostView"]) {
      potentialKeyboard = [[potentialKeyboard subviews] objectAtIndex:0];
    }                                                                                

    if ([[potentialKeyboard description] hasPrefix:@"<UIKeyboard"]) {
      keyboard = potentialKeyboard;
      break;
    }
  }

But I am not sure if this will break when the SDK changes ...

Maybe use this method and add a category to the window so that you can just always ask the window for the keyboard ... just a thought.