Add "allowCancel" to TOPasscodeViewController

Adds a new "allowCancel" property on TOPasscodeViewController that turns off
the default cancel button when set to NO, for use when the user can't proceed
in the app at all without entering a passcode.

Author: Fae Laren

TOPasscodeViewController/TOPasscodeViewController.h

@@ -82,6 +82,9 @@ NS_ASSUME_NONNULL_BEGIN
 /** Will show a 'Touch ID' or 'Face ID' (depending on `biometricType`) button if the user is allowed to log in that way. (Default is NO) */
 @property (nonatomic, assign) BOOL allowBiometricValidation;
 
+/** Will show a default 'Cancel' button if rightAccessoryButton is not set. (Default is YES) */
+@property (nonatomic, assign) BOOL allowCancel;
+
 /** Set the type of biometrics for this device to update the title of the biometrics button properly. */
 @property (nonatomic, assign) TOPasscodeBiometryType biometryType;
 

TOPasscodeViewController/TOPasscodeViewController.m

@@ -80,6 +80,7 @@ - (void)setUp
 {
     self.transitioningDelegate = self;
     self.automaticallyPromptForBiometricValidation = NO;
+    self.allowCancel = YES;
 
     if (TOPasscodeViewStyleIsTranslucent(self.style)) {
         self.modalPresentationStyle = UIModalPresentationOverFullScreen;
@@ -176,6 +177,9 @@ - (void)setUpAccessoryButtons
         [self.cancelButton setTitle:NSLocalizedString(@"Cancel", @"Cancel") forState:UIControlStateNormal];
         self.cancelButton.titleLabel.font = buttonFont;
         [self.cancelButton addTarget:self action:@selector(accessoryButtonTapped:) forControlEvents:UIControlEventTouchUpInside];
+        // If cancelling is disabled, we hide the cancel button but we still create it, because it can
+        // transition to backspace after user input.
+        self.cancelButton.hidden = !self.allowCancel;
         if (isPad) {
             self.passcodeView.rightButton = self.cancelButton;
         }
@@ -443,9 +447,17 @@ - (void)accessoryButtonTapped:(id)sender
 
 - (void)keypadButtonTapped
 {
-    NSString *title = self.passcodeView.passcode.length > 0 ? NSLocalizedString(@"Delete", @"Delete") : NSLocalizedString(@"Cancel", @"Cancel");
+    NSString *title = nil;
+    if (self.passcodeView.passcode.length > 0) {
+        title = NSLocalizedString(@"Delete", @"Delete");
+    } else if (self.allowCancel) {
+        title = NSLocalizedString(@"Cancel", @"Cancel");
+    }
     [UIView performWithoutAnimation:^{
-        [self.cancelButton setTitle:title forState:UIControlStateNormal];
+        if (title != nil) {
+            [self.cancelButton setTitle:title forState:UIControlStateNormal];
+        }
+        self.cancelButton.hidden = (title == nil);
     }];
 }