如何以编程方式检查iOS应用程序中是否存在键盘？
如何以编程方式检查iOS应用程序中是否存在键盘？
提问于 2009-09-29 04:31:35
我需要在我的iOS应用中检查键盘可见性的情况。
伪码：
if(keyboardIsPresentOnWindow) {
//Do action 1
}
else if (keyboardIsNotPresentOnWindow) {
//Do action 2
}如何检查此条件？
回答 13
Stack Overflow用户
发布于 2009-09-29 13:12:15
drawnonward的代码非常接近，但与UIKit的命名空间冲突，可以使其更易于使用。
@interface KeyboardStateListener : NSObject {
BOOL _isVisible;
}
+ (KeyboardStateListener *)sharedInstance;
@property (nonatomic, readonly, getter=isVisible) BOOL visible;
@end
static KeyboardStateListener *sharedInstance;
@implementation KeyboardStateListener
+ (KeyboardStateListener *)sharedInstance
{
return sharedInstance;
}
+ (void)load
{
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
sharedInstance = [[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;
}
@endStack Overflow用户
发布于 2009-09-29 05:38:15
在知道键盘不可见时创建UIKeyboardListener，例如从applicationDidFinishLaunching调用[UIKeyboardListener shared]。
@implementation UIKeyboardListener
+ (UIKeyboardListener) shared {
static UIKeyboardListener sListener;
if ( nil == sListener ) sListener = [[UIKeyboardListener alloc] init];
return sListener;
}
-(id) init {
self = [super init];
if ( self ) {
NSNotificationCenter *center = [NSNotificationCenter defaultCenter];
[center addObserver:self selector:@selector(noticeShowKeyboard:) name:UIKeyboardDidShowNotification object:nil];
[center addObserver:self selector:@selector(noticeHideKeyboard:) name:UIKeyboardWillHideNotification object:nil];
}
return self;
}
-(void) noticeShowKeyboard:(NSNotification *)inNotification {
_visible = true;
}
-(void) noticeHideKeyboard:(NSNotification *)inNotification {
_visible = false;
}
-(BOOL) isVisible {
return _visible;
}
@endStack Overflow用户
发布于 2015-02-17 11:06:48
使用窗口子视图层次结构作为键盘显示的指示是一种技巧。如果苹果改变他们的底层实现，所有这些答案都会被打破。
正确的方法是在应用程序范围内监控Keyboard显示和隐藏通知，例如在App Delegate中：
在AppDelegate.h中：
@interface AppDelegate : UIResponder <UIApplicationDelegate>
@property (assign, nonatomic) BOOL keyboardIsShowing;
@end在AppDelegate.m中：
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
// Monitor keyboard status application wide
self.keyboardIsShowing = NO;
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:)
name:UIKeyboardWillShowNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillBeHidden:)
name:UIKeyboardWillHideNotification object:nil];
return YES;
}
- (void)keyboardWillShow:(NSNotification*)aNotification
{
self.keyboardIsShowing = YES;
}
- (void)keyboardWillBeHidden:(NSNotification*)aNotification
{
self.keyboardIsShowing = NO;
}然后您可以使用以下命令进行检查：
BOOL keyboardIsShowing = ((AppDelegate*)[UIApplication sharedApplication].delegate).keyboardIsShowing;需要注意的是，当用户使用蓝牙或外接键盘时，键盘显示/隐藏通知不会触发。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/1490573
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