HTUpdateAggregator improves update logic in NSObject/UIView/UIViewController subclasses

• Familiar pattern of updateContent, setNeedsUpdate, and updateIfNeeded
  • Just like layoutSubviews, setNeedsLayout, and layoutIfNeeded
• Automatically trigger updates using key-value observation of properties
  • Avoids overriding setters, potentially breaking synthesized behaviors and adding boilerplate
• Aggregate update calls within runloops
• Centralized updateContent improves maintainability for most cases

Example

Implement updateContent:

- (void)updateContent
{
    self.makeLabel.text = self.make;
    self.modelLabel.text = self.model;
    self.colorNameLabel.text = self.colorName;
    self.descriptionLabel.text = self.carDescription;
    [self setNeedsLayout];
}

Implement keyPathsTriggerUpdate:

+ (NSArray *)keyPathsToTriggerUpdate
{
    return @[@"make", @"colorName", @"model", @"carDescription"];
}

That's it. When one of the keypaths changes, setNeedsUpdate is automatically called.

If you are not a UIView or UIViewController, you must call startObservingForUpdates on yourself to add the observers during initialization.

Demo

See demo in https://github.com/hoteltonight/HTKit

HTCarDetailsViewV1, V2 and V3 show incremental improvements to a simple dynamic UI component using these tools.

This sequence of improvements was discussed at NSMeetup April 2013, slides here: http://d.pr/f/jczG

Installation

The recommended installation method is cocoapods. Add this line to your Podfile:

pod 'HTGraphics'

http://cocoapods.org

SFObservers is a dependency for those who don't cocoapods.

Discussion

SFObservers is a dependecy, used to automatically remove KVO observers.

Contributions welcome!

Use it? Love/hate it?

Tweet the authors @jakejennings and @jonsibs, and check out HotelTonight's engineering blog: http://engineering.hoteltonight.com

Also, check out HotelTonight's other iOS open source:

• https://github.com/hoteltonight/HTAutocompleteTextField
• https://github.com/hoteltonight/HTRasterView
• https://github.com/hoteltonight/HTKit
• https://github.com/hoteltonight/HTGradientEasing
• https://github.com/hoteltonight/HTDelegateProxy
• https://github.com/hoteltonight/HTCoreImage