ios: adjust ui view constraint when UIKeyboard shows

src/ios/Base.lproj/Main.storyboard

@@ -163,7 +163,9 @@
                         </constraints>
                     </view>
                     <connections>
+                        <outlet property="bottomConstraint" destination="jt2-ZP-qgJ" id="nnY-MI-aZ1"/>
                         <outlet property="cipherMethod" destination="lHf-f6-QZT" id="8Z3-eA-8Al"/>
+                        <outlet property="contentView" destination="SS9-hV-cEA" id="IGX-hT-btt"/>
                         <outlet property="password" destination="pfU-fE-5kl" id="x6M-3I-sMa"/>
                         <outlet property="serverHost" destination="GsR-Z4-fTf" id="mJM-Ny-yXp"/>
                         <outlet property="serverPort" destination="1hy-kK-Mai" id="oWU-M2-gfa"/>

src/ios/YassViewController.h

@@ -26,6 +26,8 @@
 - (NSString*)getCipher;
 
 @property (weak, nonatomic) IBOutlet UILabel *status;
+@property (weak, nonatomic) IBOutlet NSLayoutConstraint *bottomConstraint;
+@property (weak, nonatomic) IBOutlet UIScrollView *contentView;
 
 
 @end

src/ios/YassViewController.mm

@@ -72,6 +72,31 @@ - (void)viewWillAppear:(BOOL)animated {
   YassAppDelegate* appDelegate =
       (YassAppDelegate*)UIApplication.sharedApplication.delegate;
   [appDelegate reloadState];
+  [[NSNotificationCenter defaultCenter] addObserverForName:UIKeyboardWillShowNotification object:nil queue:[NSOperationQueue mainQueue] usingBlock:^(NSNotification * _Nonnull notification) {
+    NSDictionary *userInfo = notification.userInfo;
+    NSTimeInterval duration = [userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];
+    CGRect keyboardEndFrame = [self.view convertRect:[userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue] toView:self.view.window];
+
+    CGRect windowFrame = [self.view convertRect:self.view.window.frame toView:self.view.window];
+    CGFloat heightOffset = (windowFrame.size.height - keyboardEndFrame.origin.y) - self.view.frame.origin.y;
+
+    self.bottomConstraint.constant = heightOffset + 20;
+
+    [UIView animateWithDuration:duration
+                     animations:^{
+      [self.view layoutIfNeeded];
+    }];
+  }];
+
+  [[NSNotificationCenter defaultCenter] addObserverForName:UIKeyboardWillHideNotification object:nil queue:[NSOperationQueue mainQueue] usingBlock:^(NSNotification * _Nonnull notification) {
+    NSDictionary *userInfo = notification.userInfo;
+    NSTimeInterval duration = [userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];
+    self.bottomConstraint.constant =  20;
+    [UIView animateWithDuration:duration
+                     animations:^{
+      [self.view layoutIfNeeded];
+    }];
+  }];
   [super viewWillAppear:animated];
 }