I had a task to animate the slider in the app on touch by smoothly enlarging the thumb. Just like Apple does in the Apple Music and Podcasts player when you start scrubbing the playback position. I spent quite a lot of time looking for a way to do it with standard tools. I really did not want to write a completely custom slider; I wanted to use the system UISlider, and in the end I managed to do exactly that.

UISlider inherits from UIControl. It lets you set your own position image for a specific state:

open func setThumbImage(_ image: UIImage?, for state: UIControlState) 

The .normal state is the regular slider state, and the .highlighted state is when we are touching the slider.

If we simply assign different images to two different states, we get a larger thumb. The only problem is that it will not be animated at all. You can animate a UIControl state transition from one state to another, but what happens is an image replacement, not a size change. I tried various transitions such as CATransition, but the best I could achieve for the state change animation was a smooth Fade In of the larger image for the .highlighted state, while what I needed was a smooth enlargement of the thumb itself.

So I had to abandon the idea of assigning two different images to different slider states. In the end I came up with this funny hack.

For convenience, let us add a function to the project that creates a circle of the required color and size and returns it as a UIImage:

extension UIImage {
    class func circle(diameter: CGFloat, color: UIColor) -> UIImage {
        UIGraphicsBeginImageContextWithOptions(CGSize(width: diameter, height: diameter), false, 0)
        let ctx = UIGraphicsGetCurrentContext()
        ctx!.saveGState()

        let rect = CGRect(x: 0, y: 0, width: diameter, height: diameter)
        ctx!.setFillColor(color.cgColor)
        ctx!.fillEllipse(in: rect)
        ctx!.restoreGState()

        let img = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return img!
    }
} 

Add a standard UISlider:

The next step is to create our own class that inherits from UISlider, and set the image in awakeFromNib():

class Slider: UISlider {
    override func awakeFromNib() {
        super.awakeFromNib()

        let positionImage = UIImage.circle(diameter: 30, color: UIColor.blue)
        self.setThumbImage(positionImage, for: .normal)
    }
} 

In Interface Builder, set the Class field of our slider to the name of our subclass (Slider). We get a slider with a position thumb of the desired color:

Now we need to add an image for the enlarged thumb that will appear on touch. We do this by simply adding a UIImageView:

class Slider: UISlider {
    /// Big position image view
    var bigImage = UIImageView()

    override func awakeFromNib() {
        super.awakeFromNib()

        let positionImage = UIImage.circle(diameter: 30, color: UIColor.blue)
        self.setThumbImage(positionImage, for: .normal)

        let positionImageBig = UIImage.circle(diameter: 60, color: UIColor.blue)
        self.bigImage.contentMode = .scaleAspectFit
        self.bigImage.clipsToBounds = false
        self.bigImage.image = positionImageBig

        self.addSubview(bigImage)
        self.bringSubview(toFront: bigImage)
    }
} 

Next, we need to use the UISlider method that calculates the frame for the thumb image:

open func thumbRect(forBounds: CGRect, trackRect: CGRect, value: Float)

The idea is to use this method to obtain and return the thumb frame without interfering with its normal inactive size (or, if you want, while interfering with it). After that we take the UIImageView with the large thumb and tell it to have the same position and the same size. This method is called continuously while we drag our UISlider, so the big indicator always stays in exactly the same place as the standard one and, for now, at exactly the same size:

class Slider: UISlider {
    // ... previous code

    /// Small indicator counted size
    var indicatorSize: CGSize? = nil

    override func thumbRect(forBounds bounds: CGRect, trackRect rect: CGRect, value: Float) -> CGRect {
        let unadjustedThumbrect = super.thumbRect(forBounds: bounds, trackRect: rect, value: value)

        let origin = unadjustedThumbrect.origin
        let size = unadjustedThumbrect.size

        if self.indicatorSize == nil && unadjustedThumbrect.size.width > 0 {
            self.bigImage.frame = unadjustedThumbrect
            self.indicatorSize = size
        }

        let bigImageSize = self.bigImage.frame.size

        self.bigImage.frame.origin = CGPoint(
            x: origin.x - (bigImageSize.width/2 - size.width/2),
            y: origin.y - (bigImageSize.height/2 - size.height/2)
        )

        self.bringSubview(toFront: bigImage)

        return unadjustedThumbrect
    }
} 

Visually you do not see any difference yet, but together with the built-in thumb we now always have an image for the enlarged state at the same position, moving together with it.

And finally, when the user touches the slider, we simply animate the enlargement of our bigImage. And, accordingly, shrink it when the touch ends. For that we use the built-in isHighlighted property of UISlider and animate when its value changes:

class Slider: UISlider {

    override var isHighlighted: Bool {
        didSet {
            // avoid situation when indicator size didn't count yet
            guard self.indicatorSize != nil else { return }

            UIView.animate(withDuration: 0.3) {
                if self.isHighlighted == true {
                    self.bigImage.transform = CGAffineTransform(scaleX: 2, y: 2)
                } else {
                    self.bigImage.transform = CGAffineTransform(scaleX: 1, y: 1)
                }
            }
        }
}

    // ..other code
} 

Done. The position thumb in the slider is now animated when interacting with it:

You can see the full code on GitHub: https://github.com/makoni/CustomUISlider

I got tired of the SMS spam that periodically comes to me — offers for loans, mortgages, and so on. While watching one of the WWDC videos, I noticed that Apple had provided an API for filtering SMS messages. If your filter triggers, such messages arrive silently, without a sound or vibration, and go into a separate spam category in Messages.

Without much hesitation, I made this filter and uploaded it to the App Store. Hopefully it will be useful to someone besides me.

I ran into a problem where a Vapor 2 project stopped compiling on Ubuntu. More precisely, one of its dependencies, Crypto. It turned out that because of an added repository containing newer versions of some libraries, it would not compile. Writing it down here — I had to downgrade:

apt install libssl-dev=1.0.2g-1ubuntu4.10
apt install openssl=1.0.2g-1ubuntu4.10

After migrating my pet project from Vapor 1 to Vapor 2 I've run benchmarks to compare performance. I didn't run benchmarks for the last version of Vapor 1.x which is 1.5.15 so I will compare Vapor 2.1.0 to results of Vapor 1.2.5 that I have from my last results.

My server:

• 2 GB RAM
• 1 CPU Core
• SSD
• 125 MBPS Out
• Ubuntu 16.04.2 LTS
• CouchDB

Benchmark from other server was launched as:

wrk -t4 -c20 -d5m https://my_url

API just gets some data from CouchDB and returns it as JSON. Vapor project has been compiled with Swift 3.1.1.

Total requests

Requests per second

Average Latency

Memory usage

Vapor 2 is about 14-15% faster than Vapor 1.2.5. And what's important - Vapor 1.2.5 memory usage grew up after benchmarks from 13.4 mb to 59.1 mb and Vapor 2 started with just 3.6 mb and its memory usage grew up to 5.3 mb. That's very impressive.

I was fighting memory leaks in a work project. Digging led me to the fact that after leaving a UIViewController, far from all memory gets released. If you open this UIViewController several times, go back, and open it again, memory consumption grows and does not get released very much.

The root of the problem turned out to be protocols and delegates. A classic mistake. In my UIViewController I use a UICollectionView with a custom cell that has a delegate. My UIViewController is the delegate for each cell. An example of implementing such a protocol and delegate on the internet and in a Swift book looks roughly like this:

// Protocol
protocol MyCollectionViewCellDelegate {
    func someFunc()
}

// UICollectionViewCell
final class MessageCollectionViewCell: UICollectionViewCell {
    var delegate: MyCollectionViewCellDelegate?
}

// UIViewController
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    // some code....
    cell.delegate = self
}

Inside the cell object we have a strong reference to the delegate (UIViewController), which results in a memory leak.

The solution is simple — make the reference to delegate weak. To do that, you have to specify that only a class can implement the protocol. Structures are out, but there is no need for them here anyway. It changes like this:

// Protocol
protocol MyCollectionViewCellDelegate: class {
    func someFunc()
}

// UICollectionViewCell
final class MessageCollectionViewCell: UICollectionViewCell {
    weak var delegate: MyCollectionViewCellDelegate?
}

After these simple changes everything became great — after navigating back from the UIViewController, memory usage returns to its initial level.

I finally finished the latest installment in the Assassin's Creed series so far.

As far as I understand, the game is built on the same engine as Assassin's Creed Unity — the same parkour system that lets you run over obstacles both upward and downward, a similar assassination mission structure with several entry points and extra sub-objectives or different ways to approach the target, skill upgrades, and so on.

This installment is, in my opinion, colorful, successful and interesting. Definitely one of the best in the whole series. However, there was one thing that confused me right away.

As soon as I launched the game, I immediately noticed that the graphics detail was awful and the screen resolution looked very low. I went into the graphics settings in the game and was stunned. For some reason the game says that my 2 GB of video memory is only enough for the lowest graphics settings and a resolution of 1280x720. That is terrible — none of the previous installments made demands like that. I understand that my video card is not top-end (AMD Radeon R9 M395X), but it is not so weak that it should deliver such miserable graphics in this game. All the previous installments played perfectly and looked great, while here it is a total failure, with completely insane GPU requirements.

The story is great. The game takes place in nineteenth-century London, and the main characters are Jacob and Evie Frye. The twins decide to take matters into their own hands and head for London, which is entirely under Templar control, to find a Piece of Eden instead of sitting idle and merely following orders from the Assassin Brotherhood.

By the way, that Brotherhood appears only once in the entire game, demanding that Jacob and Evie follow its instructions strictly and stop getting involved on their own. After that it disappears from the game entirely, and there is only one "local" Assassin left — an Indian working in London.

Jacob immediately decides to stir things up in the city. Since the Templars rule all of London through their gang, the Hanging Men, then the answer is to create your own gang and take the city back from them. Evie periodically reproaches him for indulging in the joys of a criminal life. The game is generally very good in terms of humor :)

Accordingly, the game has a fair amount of freedom of action. You can follow the main story by completing story missions, or you can do various parallel storylines. As usual, they feature historical figures such as Dickens, Darwin, and even Queen Victoria. On top of that, you can capture districts of London by doing, again, a set of missions. At first this is very impressive and looks very interesting. But after capturing 2–3 districts it becomes dull and routine. The missions themselves are interesting, but there are too many samey ones.

The game is not as colorful visually as Black Flag, but it is interesting, bloody, and has the gray atmosphere of London. On top of that, it introduces several really cool new features.

The hook. London streets are wide, in many places you cannot jump across the street, and rooftop movement is no longer as easy as it was in the early games. So we are given a grappling gun — the heroes simply fire it at the destination point and slide along the taut line. Convenient, though not especially realistic :)

Carriages. Finally, you can move around the city by transport. It immediately reminded me of GTA. You can get into any carriage — one standing empty or one driving down the street by throwing the coachman off it. Riding a carriage is much faster, and a route to the destination is drawn right on the road, showing where to drive and where to turn, taking traffic direction into account — practically GPS in augmented reality. On top of that, you can climb onto carriages and fight on them while moving. That is great: you no longer have to spend half an hour running to your destination, since the synchronization points used for fast travel are rather far apart in this game.

The gang. Members of the protagonists' gang, the Rooks, wear green, so you can always recognize them. You can take gang members along with you so they follow you. The squad size increases as you progress through the game and upgrade the gang skill tree. The gang has its own separate skill tree, and all bonuses apply specifically to the fighters — new fighter types, higher level (and strength), and so on. And the brawls during district captures, with big gangs fighting each other using brass knuckles and knives, are beautiful. In general it is very satisfying to gather a crowd and send it to beat up another crowd while you, for example, quietly slip somewhere under the noise.

Money plays an important role in the game. With money you can buy weapons, equipment and clothing. Everything can be upgraded, increasing your heroes' stats (strength, stealth, and so on).

You can also earn money through side activities — for example, I took part in boxing matches where you have to defeat several waves of opponents in fistfights. It looks great :) Besides that, you can rob, steal, and even rob a train. Or earn some money in carriage races if you are short.

The fights in the game look good, but combat has been simplified too much. Block, hit, block, hit. Almost monotonous button pressing. The only variety is the ability to shoot an opponent, throw some kind of grenade, or perform double and triple takedowns. Yes, it looks cool when during a finisher the hero kicks an enemy into the water, but you want to create some action yourself too. The fights are rather boring.

The modern-day storyline is present, but only in the form of various videos. There is little of it, it is unclear, and you do not participate in anything. I do not like that.

The main villain is kind of lame. He just sits there doing nothing, not even really giving orders to his helpers. Passive, he starts doing anything only at the very end of the game. That becomes the final battle, made to a familiar pattern — in many installments the ending follows the same scheme: find a First Civilization temple, find the artifact, then defeat the main villain who now has the artifact in his hands (that is, a superpower) while trying not to die from some incomprehensible First Civilization technology. In this installment, however, all of that is made more interesting by the fact that there are two heroes in the game at once.

Overall the game is good and it was interesting to play. Just like in Unity, there is a separate storyline dedicated to World War I. Only while in Unity the action was in Paris, here it is in London. It is interesting, but short. I think I spent most of my time on side missions and parallel storylines, barely touching the main plot. And the main plot itself is rather short, so the extra variety does not hurt.

The game is cool. If only it did not have such insane graphics requirements. I look at my screenshots and everything looks really sad. Especially compared to AC IV Black Flag. At first I thought maybe they would optimize it in later updates, but nope: the game has been out for a long time already, and Ubisoft is most likely busy making the next installment, rumors of a June announcement of which have already appeared.

Up next is DLC for this installment. Thankfully Ubisoft had a sale this weekend, so I stocked up :)

I finished another installment, Assassin's Creed Rogue.

The game is built on the same engine as Black Flag, which was very good. Even though the previous installment, AC Unity, was already on a new engine. Judging by the feel of it, this is DLC that they decided to release as a separate game.

Once again, you spend most of the game sailing a ship across different seas, only this time in northern waters. Hence the new details — ice floes that you have to break through with the ship, floating icebergs that you can (and sometimes have to) shoot with the cannon so you do not hit them and damage the ship.

The ship upgrade system is almost the same as in Black Flag. The battles are almost the same too, they just added a few details. One pleasant innovation is that during naval combat not only can you board an enemy vessel, but an enemy vessel can board you as well. A couple of times that even saved me — you are fighting several ships, you have been battered badly, it seems you are about to be sunk, and then they board you, which ends up saving you: you quickly defeat everyone in melee, repair your ship using the captured one, and calmly continue the fight with your hull strength restored.

The modern-day storyline is also similar to Black Flag — you walk around the Abstergo office, there is some kind of accident, for some reason almost everyone except you has been evacuated, you hack computers, start servers by solving puzzles, and along the way collect various information, much of it with references to previous installments.

For example, there is a short dossier on Al Mualim from the first game. Though viewed through a different lens — a Templar one.

Overall, the main changes are in the scenery. There is a lot of snow, the gameplay is slightly expanded with details from AC III about the Native American Connor — there is more tree climbing. And the world map feels larger. But all of it is dull and routine because of the boring plot.

The plot itself is just boring and muddled. Once again the Assassins prevent the Templars from finding artifacts so they cannot use them to bend the world to their will. Along the way a young Assassin becomes disillusioned with the brotherhood after taking many lives and joins the Templars. Supposedly he wants to stop the murders, but at the same time he slaughters almost everyone indiscriminately. Sadly, with such a great engine they still could not manage an interesting story. Once again there is a lot of «collect them all» stuff, only even duller.

Although the graphics have visually become cooler and prettier, there is something strange going on with the shadows in the game. All the faces look dull and creepy.

On the plus side, the game has a nice nod to the installments about Ezio Auditore — in one place you have to climb around a temple (Lisbon), jump across pillars and beams, find and pull levers to open a secret passage.

One of the most beautiful and dynamic scenes in the game is the escape from Lisbon. According to the plot, the famous earthquake that destroyed Lisbon was caused by the game's protagonist himself while he was still an Assassin. In fact, that is what changed his view of Assassin methods. This section is a fairly simple runner — just run and dodge — but it is all done beautifully.

The cities are more reminiscent of the locations from AC III — American colonies, gloomy cities.

Back to the graphics again — everything is beautiful, but what the hell is happening with the shadows? Why is everything so gloomy?

Everything is kind of yellow and dreary.

Naval battles are still great. You fire the cannons and steer the ship. The smoke from the shots blocks visibility, so you have to maneuver to see where the enemy ship ended up in order to aim again. Or fire blind, which is not bad either. The battles are just as dynamic.

The melee combat, in my opinion, became prettier and bloodier compared to AC IV Black Flag. That is nice. But the weapon set did not change: darts, sabers, pistols, a rope with a hook. Though overall it is a great set.

A lot of characters from other installments appear in the game. For example, Kenway, who, as I later understood, is the son of Edward Kenway, the main hero of AC IV Black Flag, who became a Templar and went to the American colonies to search for artifacts. He was the one who fathered a son with a local woman from a Native tribe — Connor, the hero of AC III. I have always liked that way the story connects several installments of the series.

If not for the boring plot, the game would have been great. But in the end I played it very little — I just finished the story, sailed around the world a bit and dropped it. All of this was already in Black Flag, but there it was much more colorful, interesting and fun. I did not even feel like fighting the legendary ships. I would rather install AC IV Black Flag again and play that than replay Rogue. Though who knows.

Next in line is the latest main installment — Assassin's Creed Syndicate, which I finally finished. If I have time, I will write down my impressions of it too, for the record.