SWIFT IOC

This is a simple Swift IOC container implementation. The entire implementation is contained (no pun intended) in a single Contents.swift file for quick copy-and-paste into your project.

FEATURES

• Simple API. Minimal concepts.
• Tiny file. Minimal code (less than 100 LOC w/o docs).
• One file drop-in. You don't even need any dependency manager.
• Immutable containers. Construct new ones by +-ing existing ones.
• Can be used to make hierarchical container trees.

USAGE

Register dependencies with either a singleton or a factory resolver:

// Registers a singleton object.
let resolver = singleton({ _ in GlobalServiceObject() })

// Registers a factory function.
let resolver = factory({ (resolver) -> ComplexObject in
    let co = ComplexObject()
    co.innerDependency = <-resolver
    co.invokeMethod()

    return co
})

// Registers a factory function using Swift shorthand lambda form
let resolver = factory({ Dependent(dependency: <-$0) })

Construct your container by merging Resolvers together using the plus (+) operator:

let container = singleton({ _ in ServiceOne() }) +
  singleton({ _ in ServiceTwo() }) +
  factory({ _ in InstanceService() })

// or mutable
var container = emptyContainer()
container += singleton({ _ in ServiceOne() })
container += singleton({ _ in ServiceTwo() })
//...

Then to obtain dependencies, pull it out from the container you have just created using the reverse arrow (<-) operator:

import UIKit

class MyViewController: ViewController {
  let serviceObject: GlobalServiceObject = <-container
  let anotherService: InstanceService = <-container

  override func viewDidLoad() {
    super.viewDidLoad()
    serviceObject.use()
  }
}

Additionally, dependencies can be lazy:

class X {
  lazy var cash: ExpensiveObject = <-container

  func doWork() {
    cash.work()
  }
}

Or hierarchical:

import UIKit

let topLevel = singleton({ _ in ServiceObject() })

class RootViewController: ViewController {
  let container = topLevel + singleton({ _ in ViewUtility() })

  // ...
}

Or registered out-of-order:

var container = emptyContainer()
container += factory({ One(requireTwo: <-$0 })
container += factory({ Two(requireThree: <-$0 })
container += factory({ Three() })

Enjoy!

TODOs / PR material

• Handles superclass types.
• Overrides.
• Modules system.
• Cyclic check.

SUPPORT

GitHub issue or ping me @chakrit on twitter.

LICENSE

MIT