iOS 8 custom UIActivity image black background color

问题

I am trying to add a custom UIActivity of type UIActivityCategoryAction to UIActivityController. But in iOS 8, all of them are appearing with a black background.

Is there a way to change this?

回答1:

There are 3 things to note here:

1. image background,
2. image opaqueness,
3. image size.

---

iOS 7

1. Image background:

Image background should be transparent.

2. image opaqueness

The "visible part" of the icon should be non transparent aka opaque. Note that any color information won't be preserved:

3. image size

Because the image won't be scaled by the system if too small/big, you have to provide appropriately sized image. I found image size 120px x 120px to fit perfectly.

Note: this size also takes icon padding into account.

---

iOS 8+

1. Image background:

Image background should be white to match the system UIAction icons but you can also use an arbitrary color.

2. image opaqueness

Same as in iOS 7, "visible" part of the icon should be non transparent aka opaque, however in iOS 8+ color information will be preserved.

3. image size

I am using image with size 240px x 240px, but you can apply custom sized image because system will automatically scalle-to-fill image if too small/big.

---

Wrap up

That said, if you want to support both iOS 7 and iOS 8+, you have to have 2 versions of custom UIActivity icon image.

For iOS 7 you should use 120px x 120px sized image with transparent background. Note: find the size that best suits your needs.

For iOS 8+ you should use custom sized square image with white background and "visible" part of an arbitrary colour.

Code example

- (UIImage *)activityImage
{
    if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 8.0) {
        return [UIImage imageNamed:@"activity_icon_ios8"];
    }
    else {
        return [UIImage imageNamed:@"activity_icon"];
    }
}

Hope that helps!

来源：https://stackoverflow.com/questions/25817265/ios-8-custom-uiactivity-image-black-background-color