Call update permission prompt delegate method only when needed (#2622)

The delegate method is not called if SUEnableAutomaticChecks is specified in the Info.plist (now) or if the user has responded to a permission prompt request.

Also fixes a respondsToSelector check in legacy SUUpdater adaptor (fixes #2618).

Sparkle/SPUUpdater.m

@@ -382,19 +382,18 @@ - (void)startUpdateCycle SPU_OBJC_DIRECT
 
     id<SPUUpdaterDelegate> delegate = _delegate;
 
-    // If the user has been asked about automatic checks, don't bother prompting
+    // If the user has been asked about automatic checks or the developer has overridden the setting, don't bother prompting
     // When the user answers to the permission prompt, this will be set to either @YES or @NO instead of nil
-    if ([_host objectForUserDefaultsKey:SUEnableAutomaticChecksKey] != nil) {
+    if ([_host objectForKey:SUEnableAutomaticChecksKey] != nil) {
         shouldPrompt = NO;
     }
     // Does the delegate want to take care of the logic for when we should ask permission to update?
     else if ([delegate respondsToSelector:@selector((updaterShouldPromptForPermissionToCheckForUpdates:))]) {
         shouldPrompt = [delegate updaterShouldPromptForPermissionToCheckForUpdates:self];
     }
-    // Has the user been asked already? And don't ask if the host has a default value set in its Info.plist.
-    else if ([_host objectForKey:SUEnableAutomaticChecksKey] == nil) {
+    else {
         // We wait until the second launch of the updater for this host bundle, unless explicitly overridden via SUPromptUserOnFirstLaunchKey.
-        shouldPrompt = [_host objectForKey:SUPromptUserOnFirstLaunchKey] || hasLaunchedBefore;
+        shouldPrompt = hasLaunchedBefore || [_host boolForInfoDictionaryKey:SUPromptUserOnFirstLaunchKey];
     }
 
     if (!hasLaunchedBefore) {

Sparkle/SPUUpdaterDelegate.h

@@ -137,7 +137,11 @@ SU_EXPORT extern NSString *const SUSystemProfilerPreferredLanguageKey;
 /**
  Returns whether Sparkle should prompt the user about checking for new updates automatically.
  
- Use this to override the default behavior.
+ Use this to override the default behavior, which is to prompt for permission to check for updates on second app launch
+ (if SUEnableAutomaticChecks is not specified).
+ 
+ This method is not called if SUEnableAutomaticChecks is defined in Info.plist or
+ if the user has responded to a permission prompt before.
  
  @param updater The updater instance.
  @return @c YES if the updater should prompt for permission to check for new updates automatically, otherwise @c NO

Sparkle/SUUpdater.m

@@ -292,7 +292,7 @@ - (NSString *)feedURLStringForUpdater:(SPUUpdater *)__unused updater
 - (BOOL)updaterShouldPromptForPermissionToCheckForUpdates:(SPUUpdater *)__unused updater
 {
     BOOL shouldPrompt = YES;
-    if ([_delegate respondsToSelector:@selector(updater:didFinishLoadingAppcast:)]) {
+    if ([_delegate respondsToSelector:@selector(updaterShouldPromptForPermissionToCheckForUpdates:)]) {
         shouldPrompt = [_delegate updaterShouldPromptForPermissionToCheckForUpdates:self];
     }
     return shouldPrompt;