The Simplest Checkbox UIButton

Posted on March 1, 2024 by Yonat Sharon

You don’t need to change the image on tap!

Buttons can change their own images when their state changes, so you only need to change the button state:

button.setImage(UIImage(systemName: "square"), for: .normal)
button.setImage(UIImage(systemName: "checkmark.square.fill"), for: .selected)
button.addAction(UIAction { _ in button.isSelected.toggle() }, for: .touchUpInside)

You can also setTitle() and it will all work out-of the box, though you may want to adjust the button.configuration to make it look nice.

For a full (yet short) implementation, see my gist:
CheckboxButton.swift

Find The Writing Direction Of A String

Posted on March 4, 2023 by Yonat Sharon

When you need to know if a string is right-to-left (rtl) or left-to-right (ltr) – don’t check individual characters. Instead, use the Natural Language framework, available since iOS 12 and macOS 10.14:

import NaturalLanguage

extension String {
    var isRightToLeft: Bool {
        guard let language = NLLanguageRecognizer.dominantLanguage(for: self) else { return false }
        switch language {
        case .arabic, .hebrew, .persian, .urdu:
            return true
        default:
            return false
        }
    }
}

Then just use it like this:

if "שלום and سلام".isRightToLeft {
    // do what needs to be done
}

Getting your framework version in run-time

Posted on April 4, 2022 by Yonat Sharon

Xcode 13 introduced a new behavior that breaks framework versions: When your clients upload their app, Apple changes the CFBundleShortVersionString of all frameworks to match that of the app.
(See this StackOverflow thread for example)

One way to avoid that is to hard-code your framework version. But if you you want to keep using the MARKETING_VERSION build setting, you can use the following hack.

Create a version variable for your framework, for example:

public class MyFramwork: NSObject {
    @objc static var version: String = ""
}

Then include this Objective-C file in your framework:

#import &lt;MyFramwork/MyFramwork-swift.h>

#define PROCESSOR_STRING(x) PRE_PROCESSOR_STRING_LITERAL(x)
#define PRE_PROCESSOR_STRING_LITERAL(x) @#x

@interface MyFramwork(version)
@property (class) NSString *version; // to access internal property
@end;

@interface MyFramworkLoader: NSObject
@end

@implementation MyFramworkLoader

#ifdef MARKETING_VERSION
+ (void)load {
    dispatch_async(dispatch_get_main_queue(), ^{
        MyFramwork.version = PROCESSOR_STRING(MARKETING_VERSION);
    });
}
#endif

@end

This will assign the MARKETING_VERSION value that you built you framework with, instead of an Apple-manipulated CFBundleShortVersionString value.

SwiftUI: @Binding Type Conversion

Posted on September 12, 2019 by Yonat Sharon

What can you do if a @Binding var has a different type from the @State var you want to bind to it?

For example, say you have a Slider which you bind to a Double state var, and you want to bind the same state var to an Int in another View:

struct MyView: View {
    @State private var currentStep: Double = 0.0
 
    var body: some View {
        Slider(value: $currentStep, in: 0.0 ... 9.0, step: 1.0)
        ViewWithInt(bindingInt: $currentStep) // Error: 'Binding<Double>' is not convertible to 'Binding<Int>'
    }
}

Solution: define an Int property on Double:

extension Double {
     var int: Int {
         get { Int(self) }
         set { self = Double(newValue) }
     }
 }

Then you can bind this int property:

ViewWithInt(bindingInt: $currentStep.int) // Works

Bold part of an NSAttributedString without changing the font

Posted on April 4, 2017 by Yonat Sharon

If you bold by changing the `NSFontAttributeName` you’ll have to specify the font face. If you don’t want to change the font face, use the `NSStrokeWidthAttributeName` with a negative value:

let s = NSMutableAttributedString(string: "Text with some bold part")
s.addAttribute(.strokeWidth, value: NSNumber(value: -3.0), range: NSRange(15..<20))

Result:

Text with some bold part

Auto-Compile .proto Files

Posted on December 1, 2016 by Yonat Sharon

Google’s protobuf compiler with Apple’s swift plugin converts .proto definitions to .swift implementations.

Instead of converting from the console and then including the generated file in your project, you can include the .proto file in your Xcode project, and let Xcode automatically convert it to swift and use the generated file:

Go to your target Build Rules.
Click the + above to add a custom rule: Sources with names matching: *.proto.
Use the following script:
protoc --proto_path="$INPUT_FILE_DIR" --swift_out="$DERIVED_FILE_DIR" "$INPUT_FILE_PATH"
Add to Output Files using the + below:
$(DERIVED_FILE_DIR)/$(INPUT_FILE_BASE).pb.swift
Go to Build Phases, to the Compile Sources section, and add your .proto files to the list.

xcode-proto

Paging Facebook Graph Results

Posted on April 17, 2016 by Yonat Sharon

Facebook iOS SDK provides `FBSDKGraphRequest` to get friends, posts, etc. But the results are paged: you only get the first 25 friends (or 5 posts). To get the rest you need to send a new request, not provided by `FBSDKCoreKit`:

[graphRequest startWithCompletionHandler:^(FBSDKGraphRequestConnection *connection, id result, NSError *error) {
	// first handle error and result...
	// then get the next page of results:
	NSString *nextPage = json[@"paging"][@"next"];
	if (nextPage) {
		[[[NSURLSession sharedSession] dataTaskWithURL:[NSURL URLWithString:nextPage] completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
			// parse data, handle results, and get the next page recursively.
		}] resume];
	}
}];

To simplify this, I wrote a simple extension to `FBSDKGraphRequest` that handles paging: FBSDKGraphRequest+Paging. Feel free to use it.

Usage:

FBSDKGraphRequest *friendsRequest = [[FBSDKGraphRequest alloc] initWithGraphPath:@"/me/friends" parameters:nil];
[friendsRequest startPagingWithCompletionHandler:^(id result, NSError *error) {
    // check for error...
    // use parsed result:
    NSArray *friends = result[@"data"];
}];

Succinct Auto Layout

Posted on April 28, 2015 by Yonat Sharon

Adding constraints programmatically is a verbose endeavor.

Several libraries try to solve this by adding an additional layer between your code and Auto Layout. (PureLayout,Masonry, SnapKit, Lyt, Cartography, and others.)
While they make some things easier, they still require you to learn a new system with new quirks.

Instead, I use MiniLayout — one short file that simply takes the verbosity out of AutoLayout. It does this by using default values for most of NSLayoutConstraint’s parameters, and by compressing the cumbersome view.addConstraint( NSLayoutConstraint(...) ) into a single call.

Examples:

Put label over textField

// using MiniLayout:
view.constrain(label, at: .Leading, to: textField)
view.constrain(textField, at: .Top, to: label, at: .Bottom, diff: 8)

// without MiniLayout:
view.addConstraint( NSLayoutConstraint(item: label, attribute: .Leading, relatedBy: Equal, toItem: textField, attribute: .Leading, multiplier: 1, constant: 0) )
view.addConstraint( NSLayoutConstraint(item: textField, attribute: .Top, relatedBy: Equal, toItem: label, attribute: .Bottom, multiplier: 1, constant: 8) )

Add button at the center of view

// using MiniLayout:
view.addConstrainedSubview(button, constrain: .CenterX, .CenterY)

// without MiniLayout:
view.addSubview(button)
button.setTranslatesAutoresizingMaskIntoConstraints(false)
view.addConstraint( NSLayoutConstraint(item: button, attribute: .CenterX, relatedBy: Equal, toItem: view, attribute: .CenterX, multiplier: 1, constant: 0) )
view.addConstraint( NSLayoutConstraint(item: button, attribute: .CenterY, relatedBy: Equal, toItem: view, attribute: .CenterY, multiplier: 1, constant: 0) )

MiniLayout uses the same enums and the same logic as AutoLayout, there’s nothing new to learn. It just makes the code shorter and more readable.

layoutSubviews Considered Reentrant

Posted on March 25, 2015 by Yonat Sharon

I had the weirdest bug the other day: rotating the iPhone worked fine in iOS 7, but not in iOS 8. Actually it was weirder: Some UIView instances adjusted themselves perfectly after the rotation, but some had the wrong size (even though they all had the exact same UIView subclass).

After some digging I discovered that layoutSubview was called several times during rotation, and each time the view had a different frame. Moreover, these calls were not happening sequentially! Instead, layoutSubviews was called with frame1, and before returning it was being called with frame2, and before returning form that it was called with frame3 — all for the same UIView.

There wasn’t a lot of code in my layoutSubviews, nothing that takes long. But it was apparently long enough to cause a bug in some instances.

My solution was to schedule a layout update for a split second later:

- (void)layoutSubviews
{
    [super layoutSubviews];
    [self performSelector:@selector(adjustLayout) withObject:nil afterDelay:0.01]; // avoid re-entering with different frame
}

- (void)adjustLayout
{
    if (CGRectEqualToRect(self.bounds, self.oldBounds)) return;
    // layout code here
    self.oldBounds = self.bounds;
}

The Simplest iOS Badge

Posted on March 11, 2015 by Yonat Sharon

In the past I used a UILabel subclass to show a badge. But since the dawn of flat UI, there’s no need to subclass.

Here is all the code you need:

let label = UILabel()
label.clipsToBounds = true
label.layer.cornerRadius = label.font.pointSize * 1.2 / 2
label.backgroundColor = UIColor.grayColor()
label.textColor = UIColor.whiteColor()
label.text = " Some Text "; // note spaces before and after text

All it does is set the cornerRadius of the label’s underlying CALayer, and add spaces before and after the label text. That’s it!

For nicely organized badge extension for UILabel and UIButton and UIBarButtonItem, see this GitHub gist:
Badge.swift

Yonat Sharon – Programming Notes

It's hard work to make things simple. (Sarah Allen)

Tag Archives: iOS