iOS: Get rid of some unsigned/signed comparison warnings.

apple/common/utility.m

@@ -64,7 +64,7 @@ void apple_display_alert(const char *message, const char *title)
 
 - (BOOL)isPartialStringValid:(NSString*)partialString newEditingString:(NSString**)newString errorDescription:(NSString**)error
 {
-   int i;
+   NSUInteger i;
    bool hasDot = false;
 
    if (partialString.length)

apple/iOS/browser.m

@@ -251,7 +251,7 @@ static void file_action(enum file_action action, NSString* source, NSString* tar
 
       dir_list_sort(contents, true);
    
-      for (int i = 0; i < contents->size; i ++)
+      for (size_t i = 0; i < contents->size; i ++)
       {
          const char* basename = path_basename(contents->elems[i].data);
       
@@ -427,7 +427,7 @@ static void file_action(enum file_action action, NSString* source, NSString* tar
    
       if (contents)
       {
-         int i;
+         size_t i;
          dir_list_sort(contents, true);
 
          for (i = 0; i < contents->size; i ++)

apple/iOS/menu.m

@@ -52,7 +52,7 @@ typedef void (^RAActionSheetCallback)(UIActionSheet*, NSInteger);
 
 static void RunActionSheet(const char* title, const struct string_list* items, UIView* parent, RAActionSheetCallback callback)
 {
-   int i;
+   size_t i;
    RARunActionSheetDelegate* delegate = [[RARunActionSheetDelegate alloc] initWithCallbackBlock:callback];
    UIActionSheet* actionSheet = [UIActionSheet new];
 
@@ -683,7 +683,7 @@ static void RunActionSheet(const char* title, const struct string_list* items, U
 
 - (void)willReloadData
 {
-   int i;
+   size_t i;
    RAHistoryMenu* __weak weakSelf = self;
    NSMutableArray *section = [NSMutableArray arrayWithObject:BOXSTRING("")];
    
@@ -907,7 +907,7 @@ static void RunActionSheet(const char* title, const struct string_list* items, U
 
 - (void)willReloadData
 {
-   int i;
+   size_t i;
    const core_info_list_t* core_list;
    RAFrontendSettingsMenu* __weak weakSelf = self;
    NSMutableArray* cores = (NSMutableArray*)self.coreConfigOptions;

apple/iOS/platform.m

@@ -116,7 +116,7 @@ static void handle_touch_event(NSArray* touches)
 // Keyboard handler for iOS 7
 - (id)_keyCommandForEvent:(UIEvent*)event
 {
-   int i;
+   NSUInteger i;
    // This gets called twice with the same timestamp for each keypress, that's fine for polling
    // but is bad for business with events.
    static double last_time_stamp;