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 had the same issue and tried many things to release the memory, but no luck. I just changed the code based on Matthew's suggestion. It works, no more memory problem for me including iPhone 6 Plus.

The code change is minimal. Find the change in the UILabel subclass below. If you ask me the challenge is to get the emoji images. I could not figure how gemoji (https://github.com/github/gemoji) works out yet.

    //self.text = title //what it used to be
    let hex = emojiToHex(title)  // this is not the one Matthew provides. That one return strange values starting with "/" for some emojis. 
    let bundlePath = NSBundle.mainBundle().pathForResource(hex, ofType: "png")

    // if you don't happened to have the image
    if bundlePath == nil
    {
        self.text = title
        return
    }
    // if you do have the image 
    else
    {
        var image = UIImage(contentsOfFile: bundlePath!)

        //(In my case source images 64 x 64 px) showing it with scale 2 is pretty much same as showing the emoji with font size 32.
        var cgImage = image!.CGImage
        image = UIImage( CGImage : cgImage, scale : 2, orientation: UIImageOrientation.Up  )!
        let imageV = UIImageView(image : image)

        //center
        let x = (self.bounds.width - imageV.bounds.width) / 2
        let y = (self.bounds.height - imageV.bounds.height) / 2
        imageV.frame = CGRectMake( x, y, imageV.bounds.width, imageV.bounds.height)
        self.addSubview(imageV)
    }

---

The emojiToHex() method Matthew provides returns strange values starting with "/" for some emojis. The solution at the given link work with no problems so far. Convert emoji to hex value using Swift

func emojiToHex(emoji: String) -> String
{
    let uni = emoji.unicodeScalars // Unicode scalar values of the string
    let unicode = uni[uni.startIndex].value // First element as an UInt32

    return String(unicode, radix: 16, uppercase: true)
}

---------- AFTER SOME TIME----

It turned out this emojiToHex method does not work for every emoji. So I end up downloading all emojis by gemoji and map each and every emoji image file (file names are like 1.png, 2.png, etc) with the emoji itself in a dictionary object. Using the following method instead now.

func getImageFileNo(s: String) -> Int
{
        if Array(emo.keys).contains(s)
        {
             return emo[s]!
        }   
        return -1
}