Add a 'hide keyboard' button whenever the iOS keyboard is shown

platform/ios/ios_loader.m

@@ -13,6 +13,7 @@
 */
 
 #import <Foundation/Foundation.h>
+#import <UIKit/UIKit.h>
 
 #include <SDL3/SDL_main.h>
 
@@ -30,8 +31,141 @@
 #define LANGUAGE "en_US.UTF-8"
 #define LUA_ERROR "failed to run lua chunk: %s\n"
 
+@interface KOKeyboardDismissOverlay : NSObject
+@property (nonatomic, strong) UIButton *button;
+@property (nonatomic, assign) CGFloat keyboardTopY;
+@end
+
+@implementation KOKeyboardDismissOverlay
+
++ (instancetype)shared {
+    static KOKeyboardDismissOverlay *overlay;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        overlay = [[KOKeyboardDismissOverlay alloc] init];
+        overlay.keyboardTopY = CGFLOAT_MAX;
+    });
+    return overlay;
+}
+
+- (void)start {
+    NSNotificationCenter *nc = NSNotificationCenter.defaultCenter;
+    [nc addObserver:self selector:@selector(onKeyboardWillChangeFrame:)
+               name:UIKeyboardWillChangeFrameNotification object:nil];
+    [nc addObserver:self selector:@selector(onKeyboardWillChangeFrame:)
+               name:UIKeyboardDidChangeFrameNotification object:nil];
+    [nc addObserver:self selector:@selector(onKeyboardDidHide:)
+               name:UIKeyboardDidHideNotification object:nil];
+}
+
+- (UIWindow *)keyWindow {
+    UIWindow *win = nil;
+    for (UIScene *scene in UIApplication.sharedApplication.connectedScenes) {
+        if (![scene isKindOfClass:[UIWindowScene class]]) continue;
+        if (scene.activationState != UISceneActivationStateForegroundActive
+            && scene.activationState != UISceneActivationStateForegroundInactive) {
+            continue;
+        }
+        for (UIWindow *w in ((UIWindowScene *)scene).windows) {
+            if (w.isKeyWindow) { win = w; break; }
+        }
+        if (!win && ((UIWindowScene *)scene).windows.count > 0) {
+            win = ((UIWindowScene *)scene).windows.firstObject;
+        }
+        if (win) break;
+    }
+    return win;
+}
+
+- (UIButton *)ensureButtonInWindow:(UIWindow *)window {
+    if (!self.button) {
+        self.button = [UIButton buttonWithType:UIButtonTypeSystem];
+        self.button.backgroundColor = [UIColor colorWithWhite:0 alpha:0.55];
+        [self.button setTitle:@"Hide keyboard" forState:UIControlStateNormal];
+        [self.button setTitleColor:UIColor.whiteColor forState:UIControlStateNormal];
+        self.button.titleLabel.font = [UIFont boldSystemFontOfSize:14];
+        self.button.contentEdgeInsets = UIEdgeInsetsMake(7, 10, 7, 10);
+        self.button.layer.cornerRadius = 10;
+        self.button.layer.masksToBounds = YES;
+        [self.button addTarget:self action:@selector(onDismissTap)
+              forControlEvents:UIControlEventTouchUpInside];
+    }
+    if (self.button.superview != window) {
+        [self.button removeFromSuperview];
+        [window addSubview:self.button];
+    }
+    [window bringSubviewToFront:self.button];
+    return self.button;
+}
+
+- (void)positionButtonInWindow:(UIWindow *)window {
+    if (!window || !self.button || self.keyboardTopY == CGFLOAT_MAX) return;
+    [self.button sizeToFit];
+    CGFloat pad = 12;
+    CGFloat btnW = CGRectGetWidth(self.button.bounds) + 12;
+    CGFloat btnH = MAX(CGRectGetHeight(self.button.bounds) + 8, 38);
+    CGFloat maxX = CGRectGetWidth(window.bounds) - pad - btnW;
+    CGFloat minY = window.safeAreaInsets.top + pad;
+    CGFloat y = self.keyboardTopY - pad - btnH;
+    if (y < minY) y = minY;
+    self.button.frame = CGRectMake(MAX(pad, maxX), y, btnW, btnH);
+}
+
+- (void)onKeyboardWillChangeFrame:(NSNotification *)note {
+    UIWindow *window = [self keyWindow];
+    if (!window) return;
+
+    CGRect kbFrameScreen = [note.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue];
+    CGRect kbFrame = [window convertRect:kbFrameScreen fromWindow:nil];
+
+    BOOL keyboardVisible = CGRectGetMinY(kbFrame) < CGRectGetHeight(window.bounds);
+    if (!keyboardVisible) {
+        return;
+    }
+
+    self.keyboardTopY = CGRectGetMinY(kbFrame);
+
+    UIButton *button = [self ensureButtonInWindow:window];
+    [self positionButtonInWindow:window];
+
+    NSTimeInterval duration = [note.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];
+    NSInteger curve = [note.userInfo[UIKeyboardAnimationCurveUserInfoKey] integerValue];
+    UIViewAnimationOptions options = ((UIViewAnimationOptions)curve << 16) | UIViewAnimationOptionBeginFromCurrentState;
+
+    if (button.hidden) {
+        button.alpha = 0;
+        button.hidden = NO;
+        [UIView animateWithDuration:duration delay:0 options:options animations:^{
+            button.alpha = 1;
+        } completion:nil];
+    } else {
+        [UIView animateWithDuration:duration delay:0 options:options animations:^{
+            button.alpha = 1;
+            [self positionButtonInWindow:window];
+        } completion:nil];
+    }
+}
+
+- (void)onKeyboardDidHide:(NSNotification *)note {
+    if (!self.button || self.button.hidden) return;
+    self.button.alpha = 0;
+    self.button.hidden = YES;
+    self.keyboardTopY = CGFLOAT_MAX;
+}
+
+- (void)onDismissTap {
+    UIWindow *window = [self keyWindow];
+    [window endEditing:YES];
+}
+
+@end
+
 int main(int argc, char *argv[]) {
     @autoreleasepool {
+        dispatch_async(dispatch_get_main_queue(), ^{
+            [[KOKeyboardDismissOverlay shared] start];
+        });
+
         NSString *resourcePath = [[NSBundle mainBundle] resourcePath];
         if (!resourcePath) {
             fprintf(stderr, "[%s]: NSBundle resourcePath is nil\n", LOGNAME);