Swift WeakArray

WeakArray offers a collection type that behaves like a Swift Array, but will not retain any of its objects.

Installation

WeakArray is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod "WeakArray"

Usage

First make sure to import WeakArray:

import WeakArray

When creating a weak array, specify the collection type as you would with an Array:

typealias myType = AnyObject
var a: WeakArray<MyType> = []

You can also use array literals to create a WeakArray, but if you specify any values you'll need to unwrap your optionals with !:

var view: UIView? = UIView()
var a: WeakArray<UIView> = [view!]

Otherwise a WeakArray works much like an Array:

var a: WeakArray<AnyObject> = []

var view: UIView? = UIView()

// Append
a.append(view)

// Replace with index
a[0] = view

// Replace with range
a[0...1] = [view, view]

// Remove Last
a.removeLast()

// Remove at index
var view: UIView? = a.removeAtIndex(0)

// Insert at index
a.insert(view, atIndex: 0)

// isEmpty and count
if (!a.isEmpty) {
	println("Count: \(a.count)")
}

// First and Last
var first: AnyObject? = a.first
var last: AnyObject? = a.last

// Append WeakArray
var b: WeakArray<AnyObject>() = []
a += b

// Or append a standard library Array
var c: [AnyObject] = []
a += c

Most of the methods you'll find in the Slice struct are implemented on WeakArray, so if there's an Array method you need, it is probably implemented. If you find a need for any of the few that are not implemented, let me know.

You can also enumerate over a WeakArray like you would an Array, but keep in mind it will skip over nil values while count will include them, so count may not match the number of enumerations you get.

func testIterationIsNotInterruptedByNilObject() {
    var a = WeakArray<UIView>()
    var obj1: UIView? = UIView()
    var obj2: UIView? = UIView()
    var obj3: UIView? = UIView()
    a.append(obj1)
    a.append(obj2)
    a.append(obj3)
    obj2 = nil
    var i = 0     
    for value in a {
        i++
    }
    XCTAssert(a.count == 3, "")
    XCTAssert(i == 2, "")
}

Version History

v0.4

• Updated to Swift 3
• Made available via cocoapods

v0.3

• Update for Swift 1.0. Thanks to Mazyod in Pull Request #1.
• Implemented more Slice methods.
• Added equality operator overload.

v0.2

• Update to match beta 5 array changes
• Use ArrayLiteralConvertible

v0.1

• Released!

Author

David Mauro, [email protected]

License

WeakArray is available under the Apache license. See the LICENSE file for more info.