feat: enhance backBarButtonItem, Adapt iOS13

TZImagePickerController/TZImagePickerController/TZPhotoPickerController.m

@@ -90,7 +90,13 @@ static CGFloat itemMargin = 5;
         tzImagePickerVc.navLeftBarButtonSettingBlock(leftButton);
         self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:leftButton];
     } else if (tzImagePickerVc.childViewControllers.count) {
-        [tzImagePickerVc.childViewControllers firstObject].navigationItem.backBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:[NSBundle tz_localizedStringForKey:@"Back"] style:UIBarButtonItemStylePlain target:nil action:nil];
+        UIBarButtonItem *backItem = [[UIBarButtonItem alloc] initWithTitle:[NSBundle tz_localizedStringForKey:@"Back"] style:UIBarButtonItemStylePlain target:nil action:nil];
+        backItem.tintColor = tzImagePickerVc.barItemTextColor;
+        NSMutableDictionary *textAttrs = [NSMutableDictionary dictionary];
+        textAttrs[NSForegroundColorAttributeName] = tzImagePickerVc.barItemTextColor;
+        textAttrs[NSFontAttributeName] = tzImagePickerVc.barItemTextFont;
+        [backItem setTitleTextAttributes:textAttrs forState:UIControlStateNormal];
+        [tzImagePickerVc.childViewControllers firstObject].navigationItem.backBarButtonItem = backItem;
     }
     _showTakePhotoBtn = _model.isCameraRoll && ((tzImagePickerVc.allowTakePicture && tzImagePickerVc.allowPickingImage) || (tzImagePickerVc.allowTakeVideo && tzImagePickerVc.allowPickingVideo));
     // [self resetCachedAssets];

TZImagePickerController/ViewController.m

@@ -257,6 +257,8 @@
         return;
     }
     TZImagePickerController *imagePickerVc = [[TZImagePickerController alloc] initWithMaxImagesCount:self.maxCountTF.text.integerValue columnNumber:self.columnNumberTF.text.integerValue delegate:self pushPhotoPickerVc:YES];
+    // imagePickerVc.barItemTextColor = [UIColor redColor];
+    // imagePickerVc.naviBgColor = [UIColor whiteColor];
     // imagePickerVc.navigationBar.translucent = NO;
     
 #pragma mark - 五类个性化设置，这些参数都可以不传，此时会走默认设置