Basic iOS Cheat Sheet for Android Developers
This is a short cheat sheet that I created to improve communication in mobile development. As Android reference I used Kotlin but it should be easy to understand for Java developers too.
Language differences
Objective C is the Java of iOS whereas Swift is very similar to Kotlin. Like Kotlin in Android, Swift is a preferred language for new projects. Swift is a newer, modern language developed by Apple to make life easier for developers. Despite that Objective C is still popular and according to data from JetBrains in 2019, almost 50% of iOS developers still know Objective C.
Kotlin vs Swift
Here I covered Kotlin equivalents in Swift. Note that these equivalents are not identical, usually have small differences.
Note that both Garbage Collection and ARC manage memory but work in completely different ways.
| Android | iOS |
|---|---|
| null | nil |
| val | let |
| var | var |
| let | if let |
| this | self |
| fun | func |
| when | switch |
| Map | Dictionary |
| Nullable | Optional |
| Pair, Triple, etc. | Tuple |
| listener | delegate |
| interface | protocol |
| SQLite/Room | Core Data |
| Garbage Collection | Automatic Reference Counting |
Framework differences
Lifecycle
Both Android and iOS Frameworks have a lifecycle. But in iOS, there are 2 important functions that don’t exist.
onSaveInstanceState/onRestoreInstanceState -> doesn’t exist
onActivityResult -> doesn’t exist. You have to use Navigation Controller with delegates (listeners).
Also, note that it’s tough to compare lifecycles from Android and iOS. I think that more detailed comparison deserves a separate article.
| Android | iOS |
|---|---|
| onCreate | loadView (loading view manually) |
| onStart and onResume | viewDidLoad |
| app running | viewWillAppear |
| app running | viewDidAppear |
| onPause and onStop | viewWillDisappear |
| onDestroy | viewDidUnload |
Creating layouts
iOS is nothing like Android when it comes to layouts. In iOS, most of the layout oriented work is done using a mouse (like in the ‘Design’ mode in Android Studio) and Swift. For layouts you can use:
1. XIB (XML Interface Builder) files. An older way to create layouts but it’s not outdated. This way every view layout has own XIB file.
2. Storyboards (one file with many views and navigation). Introduced in iOS 5. Manage many views and their navigation in one file.
Build tools and libraries
Gradle’s equivalent is Cocoapods. The former one is a build tool used (not only) for Android apps also used in IDEs other than Android Studio. The latter one is a tightly coupled to XCode IDE.
| Android | iOS |
|---|---|
| Android SDK | Cocoa Touch |
| Gradle | XCode Tools + Cocoapods |
| OkHttp | AFNetworking/Alamofire/URLSession |
| Picasso/Glide | SDWebImage/KingFisher |
| Timber | CocoaLumberjack |
| RxJava/RxKotlin | RxSwift/Bond |
| Retrofit | Moya |
| GSON/Moshi | SwiftyJSON/Codable |
| Spek | Quick |
View differences
Note that iOS doesn’t have ViewGroups because they are regular Views.
| Android | iOS |
|---|---|
| TextView | Label |
| single-line EditText | TextField |
| multi-line scrollable EditText | TextView |
| simple RecyclerView | TableView |
| customizable RecyclerView | CollectionView |
| Popup menu | Context menu |
| Bottom sheet | Action menu |
| ViewPager | PageViewController |
| Seek bar | Slider |
| View.VISIBLE/View.INVISIBLE | isHidden |
| View.GONE | StackView or constraints |
| enabled | userInteractionEnabled |
| Spinner | PickerView |
| ProgressView | ProgressView (also Spinner) |
Summary
It’s good to know Android equivalents in iOS. Usually, it’s better to communicate using names well known in programming, not only in your framework. But it’s not always possible or just doesn’t happen.
Download this free cheat sheet in PDF HERE.
Update: Check out r/androiddev Reddit discussion about this article which supplements it and brings many good ideas.
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Very good article sir
Great and very useful article, thanks!
I’d just like to point out that the equivalent to Android’s “multi-line scrollable EditText” would really be UITextView, not EditText.
Thanks Jonathan, right, it should be TextView. I just updated it
Great article, minor correction on Libraries you mistyped Gradle instead of Glide.
Thanks Lucas. I think that I fixed it yesterday. Maybe it wasn’t updated properly. I will recheck it.
Have to point out, creating layouts can be done programatically (constrains / anchors / stacks), which is much more advance than any interface builder by achieving reusability and scalability. (Plus real developer/engineer don’t program by mouse.)
Thanks, Eisen. Right, I thought that it was covered by ‘and Swift’ but I should probably add a clarifying note.
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