Using AutoLayout with UIView Subclasses in Playgrounds

myview1x

Playgrounds on the Mac and iPad are a great way to develop quick prototypes for new classes. Recently I had the need to create a UIView subclass that contained a few labels. Unfortunately, I couldn’t get my labels to display in the playground. When I used a UIViewController instead of a UIView, everything displayed properly. However, when I changed the parent class to UIView and made the few appropriate changes, my background color changed but my labels no longer appeared. So, instead of seeing this:

view_goal

I was seeing this:

view_problem

My initial thought was to configure the label in layoutSubviews() but the result was still the same.

It turns out that the labels will not autolayout inline within the playground.  You must use the PlaygroundSupport module and the liveView window:

import UIKit
import PlaygroundSupport

class MyView: UIView {

  ...

}

let v = MyView(frame: CGRect(x: 0, y: 0, width: 200, height: 150))
PlaygroundPage.current.liveView = v

Here’s a complete example:

import UIKit
import PlaygroundSupport

class MyView: UIView {
    
    let label = UILabel()
    
    private func setup() {
        self.backgroundColor = UIColor.green

        label.translatesAutoresizingMaskIntoConstraints = false
        label.text = "Hello world"
        label.textAlignment = .center
        self.addSubview(label)
        
        let margins = self.layoutMarginsGuide
        
        label.leadingAnchor.constraint(equalTo: margins.leadingAnchor, constant: 0).isActive = true
        label.trailingAnchor.constraint(equalTo: margins.trailingAnchor, constant: 0).isActive = true
        label.topAnchor.constraint(equalTo: margins.topAnchor, constant: 0).isActive = true
        label.bottomAnchor.constraint(equalTo: margins.bottomAnchor, constant: 0).isActive = true
        
    }
    
//    override func layoutSubviews() {
//    }
    
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        setup()

    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

let v = MyView(frame: CGRect(x: 0, y: 0, width: 200, height: 100))
PlaygroundPage.current.liveView = v
v

Smartwatch Sales Are Tanking

Well, at least if you believe the latest click-bait headline from TechCrunch, the smartwatch revolution could be over before it even started.

The article points out that the new Watch was only available for the last 2 weeks of the quarter, and everyone was waiting for it, so it depressed sales. Fitbit sales are skyrocketing because people want a device to help improve their health:


(source)

Apple is trying to entice that market with its new release, so we should expect quite a bit of growth.

Anyway, as I pointed out last year, health and safety will drive sales.

Personally, I’ve used my Watch to help me lose some weight:

Now I’m using my Watch to help train for my first 10k:

10k_training

macOS Sierra 10.12.1 Keyboard Issue

When I upgraded to the latest version of macOS, a few of the keys on my external mechanical keyboards stopped working. Specifically, the ‘h’ and ‘i’ keys were reversed. In other words, pressing i registered an h and pressing h registered an i. In addition, the ‘a’ key didn’t register any key press.

Fortunately, the fix only takes a minute. First, open your System Preferences then choose Keyboard.   Next, click the “Modifier Keys…” button:

 

keyboard

Finally, with your external keyboard selected, click “Restore Defaults”:

reset

Swift Cookbook Updated to Swift 3.0 Syntax

I updated my online Swift Cookbook to the 3.0 syntax.

Here are the current topics:

I also added a Github repo where all the sections are in one playground. In the near future, I hope to add sections for web, regular expressions, and files. Let me know if there are any other topics that interest you.

Functional Swift: Using Array filter and forEach functions

Recently, I started learning a couple of functional languages through online MOOCs:

Swift isn’t classified as a functional language. However, that doesn’t mean we can’t use lessons learned from functional programming to improve our code. In this article, I illustrate a few ways my programming has changed after a couple of weeks of functional programming.

[].filter

There are many places in my code that looked something like this snippet:

self.retestQuestions = []

for q in questionList {
    if !q.isAnsweredCorrectly {
        self.retestQuestions.append(q)
    }
}

This translates to one line of Swift code:

let retestQuestions = questionList.filter({!$0.isAnsweredCorrectly})

In the past, I’ve used filter() to replace NSPredicate statements, which I used extensively in Objective C. In my first conversion to Swift, I directly translated my Objective C to Swift then cast my Swift array back to an NSArray to get the filter to work. Roughly my code looked like this:

let predicate = NSPredicate(format: "numWordsInGroup >= \(minWordCount) and  numPicturesInGroup >= \(minPictureCount)")

let answer = (a1 as NSArray).filtered(using: predicate)

Embracing the Array filter() function makes a lot more sense:

let answer = a1.filter({$0.numWordsInGroup >= minWordCount && $0.numPicturesInGroup >= minPictureCount})

After only a couple of weeks of functional programming, I’ve noticed many places in my code where this example, and other

[].forEach

The forEach() function isn’t a functional concept. However, without going into detail, my functional programming has led me to prefer using the Array forEach function more often. Here are several snippets from my code:

Add subviews to parent

[pronounView, answerWellView, answerConjugationView].forEach {self.mainContainerView.addSubview($0)}

Update: Someone pointed out on Reddit that this can be simplified:

// Simply pass func to apply to each element
[pronounView, answerWellView, answerConjugationView].forEach (mainContainerView.addSubview)

Active constraints

[c1, c2].forEach {NSLayoutConstraint.activate($0)}

Applying the same concept of passing the function as an argument to forEach(), activating constraints is even simpler.

[c1, c2].forEach(NSLayoutConstraint.activate) 

translatesAutoresizingMaskIntoConstraints and addSubviews

[answer1Btn, answer2Btn, answer3Btn, answer4Btn].forEach {
    $0.translatesAutoresizingMaskIntoConstraints = false
    self.cardFrontSubView.addSubview($0)
}

Disable and hide buttons

[answer1Btn,answer1Btn,answer3Btn,answer4Btn].forEach {
    $0.isEnabled = false
    $0.isHidden = false
}

Conclusion

I’ve just finished the second week, of a six week, Haskell MOOC. Hopefully, soon I’ll be using more functional concepts and my code will be “cleaner”, and more importantly contain fewer bugs.

Disabling Activity Tracing in Xcode 8

In Xcode 8, every time you run your app, there is additional logging information in the debugging window that looks similar to this:

2016-09-29 12:37:04.826400 LosVerbos[24208:17542891] subsystem: com.apple.UIKit, category: HIDEventFiltered, enable_level: 0, persist_level: 0, default_ttl: 0, info_ttl: 0, debug_ttl: 0, generate_symptoms: 0, enable_oversize: 1, privacy_setting: 2, enable_private_data: 0
2016-09-29 12:37:04.833232 LosVerbos[24208:17542891] subsystem: com.apple.UIKit, category: HIDEventIncoming, enable_level: 0, persist_level: 0, default_ttl: 0, info_ttl: 0, debug_ttl: 0, generate_symptoms: 0, enable_oversize: 1, privacy_setting: 2, enable_private_data: 0
2016-09-29 12:37:04.844944 LosVerbos[24208:17542886] subsystem: com.apple.BaseBoard, category: MachPort, enable_level: 1, persist_level: 0, default_ttl: 0, info_ttl: 0, debug_ttl: 0, generate_symptoms: 0, enable_oversize: 0, privacy_setting: 0, enable_private_data: 0

xcode

While this may be useful at some point, I find that it makes it harder to see my own debugging messages. These messages can be disabled by setting an environment variable in your schema: OS_ACTIVITY_MODE disable

 

schema
More on Apple’s new logging: WWDC 2016 – Session 721 – iOS, macOS – Unified Logging and Activity Tracing

My iOS 10 and Swift 3 Refactor List

I used an early beta of Xcode 8 to begin my conversion to Swift 3, which led to some issues so I had to do a lot of manual changes. Actually the conversion tool still works well a line at a time. Next Error followed by Return (CMD-‘, Return) is quite handy.

I thought it would be great to track them and keep a list in one place.

layerClass() method is now a variable:

override public class func layerClass() -> AnyClass {
    return CAEmitterLayer.self
}

override public class var layerClass: AnyClass {
    return CAEmitterLayer.self
}

Method signature in AppDelegate changed to:

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        return true
    }

Still unresolved: ??

CGAffineTransform.scale(transform, scale, scale)
CGAffineTransform.scaledBy(transform, scale, scale) ???
transform = CGAffineTransform(scaleX: scale, y:scale)

CGContextSetRGBStrokeColor(context, 1.0, 0.0, 0.0, 1.0)
context.setStrokeColor(red: 1, green: 0, blue: 1, alpha: 1)
[color getRed:&red0 green:&green0 blue:&blue0 alpha:&alpha0];
       var red0:CGFloat = 0
        var green0:CGFloat = 0
        var blue0:CGFloat = 0
        var alpha0:CGFloat = 0
color.getRed(&red0, green: &green0, blue: &blue0, alpha: &alpha0)
NSMakeRange(col, 1) // Unresolved
substringWithRange()
let x = rowString.substring(with: <#T##Range#>)
UIFont *aFont = [UIFont fontWithName:"American Typewriter" size:fontSize]
let aFont = UIFont(name:"American Typewriter", size:fontSize)
NSDictionary *attributes = @{NSFontAttributeName:  aFont}
let attributes = [NSFontAttributeName:  aFont]
UIRectCornerAllCorners
UIRectCorner.allCorners
xmlText.componentsSeparatedByString("\n")
xmlText.components(separatedBy: "\n")
anArray.joinWithSeparator(",")
anArray.joined(separator: ",")
String(contentsOfURL: xmlUrl)
String(contentsOf: xmlUrl)
url.componentsSeparatedByString("/")
url.components(separatedBy: "/")
"  foobar  ".stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceCharacterSet())
"  foobar  ".trimmingCharacters(in: NSCharacterSet.whitespaces)
NSTextAlignment.Center
NSTextAlignment.center
forState: .Normal
forState: .normal
.TouchUpInside 
.touchUpInside
url.rangeOfString("github.com")
url.contains("github.com")
// https://www.hackingwithswift.com/swift3
stringByReplacingOccurrencesOfString(" ", withString:"_")
"Hello, world".replacingOccurrences(of: "Hello", with: "Goodbye")
// https://swift.org/migration-guide/
DispatchQueue.GlobalAttributes.qosDefault
        DispatchQueue.global(qos: DispatchQoS.QoSClass.default).async {

}

UIApplication.sharedApplication().
UIApplication.shared.

UIDevice.currentDevice().
UIDevice.current.
UIBezierPath(ovalInRect
UIBezierPath(ovalIn

touchesBegan() signature changed?

    override func touchesBegan(_ touches: Set, with event: UIEvent?) {
            if let touch = touches.first {
                let point = touch.location(in: self.superview)
            }

    }

moveToPoint()
move(to:
addLineToPoint()        
addLine(to: 
closePath()
close()
CGGradientCreateWithColors
CGColorSpaceCreateDeviceRGB
drawInRect
.draw(in: 
CGRectGetMaxX
CGRectGetMaxY

self.maxX
self.maxY
CGRectGetMidX()
CGRectGetMidY()

self.midX
self.midY
CGContextStrokePath(context)
context.strokePath()
CGContextSetLineWidth(context, 20)
context.setLineWidth(20)
CGRectInset()
self.bounds.insetBy(dx: 3, dy: 3)
self.view.bringSubviewToFront(cardFront)
self.view.bringSubview(toFront: cardFront)

self.tableView.registerClass(UITableViewCell.self, forCellReuseIdentifier:CellIdentifier)

self.tableView.register(UITableViewCell.self, forCellReuseIdentifier:CellIdentifier)

self.showViewController(viewController, sender: self)
self.show(viewController, sender: self)
lowercaseString
lowercased()
//http://stackoverflow.com/questions/38964264/openurl-in-ios10

UIApplication.shared.openURL(URL(string: appStoreUrl)!)
UIApplication.shared.open(URL(string:appStoreUrl)!, options: [:])

type(of:)

CGColorRef

UIGraphicsPushContext(context);
UIGraphicsPopContext();

context.saveGState()
context.restoreGState()
CalendarIdentifierGregorian
Calendar.Identifier.gregorian
Calendar.currentCalendar()
Calendar.current
CalendarOptions
Calendar.Options
.dateFromComponents()
.date(from:)
.dateByAddingComponents()
Calendar.current.date(byAdding: dateComponents, to: )