How to clear font cache filled with emoji characters?

Question

I am developing keyboard extension for iPhone. There is an emoji screen smilar to Apples own emoji keyboard that shows some 800 emoji characters in UICollectionView

Answer 1

I ran into the same issue and fixed it by dumping the .png from /System/Library/Fonts/Apple Color Emoji.ttf and using UIImage(contentsOfFile: String) instead of a String.

I used https://github.com/github/gemoji to extract the .png files, renamed the files with @3x suffix.

func emojiToHex(emoji: String) -> String {
    let data = emoji.dataUsingEncoding(NSUTF32LittleEndianStringEncoding)
    var unicode: UInt32 = 0
    data!.getBytes(&unicode, length:sizeof(UInt32))
    return NSString(format: "%x", unicode) as! String
}

let path = NSBundle.mainBundle().pathForResource(emojiToHex(char) + "@3x", ofType: "png")
UIImage(contentsOfFile: path!)

UIImage(contentsOfFile: path!) is properly released so the memory should stay at a low level. So far my keyboard extension hasn't crashed yet.

If the UIScrollView contains a lot of emoji, consider using UICollectionView that retains only 3 or 4 pages in cache and releases the other unseen pages.