Fixed bug 4726 - Fix for tvOS GetPrefPath

Caleb Cornett

Unlike iOS and macOS, tvOS does not have any persistent local storage. In fact, the ApplicationSupport directory pointed to by the existing Cocoa GetPrefPath() throws an error whenever any attempt is made to access it. To get any local storage on an Apple TV, our only option is to use a temporary cache directory.

This patch changes the tvOS PrefPath to this cache directory and also logs a critical warning that this if developers want their save data to persist across game sessions, they must use some form of iCloud storage.

src/filesystem/cocoa/SDL_sysfilesystem.m

@@ -32,6 +32,7 @@
 #include "SDL_error.h"
 #include "SDL_stdinc.h"
 #include "SDL_filesystem.h"
+#include "SDL_log.h"
 
 char *
 SDL_GetBasePath(void)
@@ -80,7 +81,27 @@ SDL_GetPrefPath(const char *org, const char *app)
     }
 
     char *retval = NULL;
+#if !TARGET_OS_TV
     NSArray *array = NSSearchPathForDirectoriesInDomains(NSApplicationSupportDirectory, NSUserDomainMask, YES);
+#else
+    /* tvOS does not have persistent local storage!
+     * The only place on-device where we can store data is
+     * a cache directory that the OS can empty at any time.
+     *
+     * It's therefore very likely that save data will be erased
+     * between sessions. If you want your app's save data to
+     * actually stick around, you'll need to use iCloud storage.
+     */
+
+    static SDL_bool shown = SDL_FALSE;
+    if (!shown)
+    {
+        shown = SDL_TRUE;
+        SDL_LogCritical(SDL_LOG_CATEGORY_SYSTEM, "tvOS does not have persistent local storage! Use iCloud storage if you want your data to persist between sessions.\n");
+    }
+
+    NSArray *array = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
+#endif /* !TARGET_OS_TV */
 
     if ([array count] > 0) {  /* we only want the first item in the list. */
         NSString *str = [array objectAtIndex:0];