PublishedKVO

PublishedKVO provides Apples Combine @Published for class-types using Key-Value-Observing (KVO requires classes to be NSObject-based). @PublishedKVO automatically publishes objects based on one or mutliple key paths. Attention: When using with SwiftUI unexpected results may occur since this publisher usually emits values after they are set inside the object (and before if the variable is overwritten/re-assigned), not always before as with the structs willSet-based @Published - this is mostly related to SwiftUIs diffing and/or animation features, probably.

Requirements

• Swift >= 5
• iOS >= 13
• macOS >= 10.15
• tvOS >= 13
• watchOS >= 6

Installation

Swift Package Manager

The Swift Package Manager is a tool for automating the distribution of Swift code and is integrated into the swift compiler.

Add the Package URL https://github.com/matis-schotte/PublishedKVO.git in Xcodes project viewer. Adding it to another Package as a dependency is as easy as adding it to the dependencies value of your Package.swift.

dependencies: [
    .package(url: "https://github.com/matis-schotte/PublishedKVO.git", from: "0.1.0")
]

Usage

class Example {
    @PublishedKVO(\.completedUnitCount)
    var progress = Progress(totalUnitCount: 2)
    
    @Published
    var textualRepresentation = "text"
}

let ex = Example()

// Set up the publishers
let c1 = ex.$progress.sink { print("\($0.fractionCompleted) completed") }
let c1 = ex.$textualRepresentation.sink { print("\($0)") }

// Interact with the class as usual
ex.progress.completedUnitCount += 1
// outputs "0.5 completed"

// And compare with Combines @Published (almost°) same behaviour
ex.textualRepresentation = "string"
// outputs "string"

ex.$progress.emit() // Re-emits the current value
ex.$progress.send(ex.progress) // Emits given value

° See Attention comment from above about SwiftUI and the following example:

class Example {
    @PublishedKVO(\.completedUnitCount)
    var progress1 = Progress(totalUnitCount: 5)
    
    @Published
    var progress2 = Progress(totalUnitCount: 5)
    
    @Published
    var progress3 = "0.0"
}

let ex = Example()

// Class using @PublishedKVO
let c1 = ex.$progress1.sink { print("$progress1 incomming \($0.fractionCompleted) actual \(ex.progress1.fractionCompleted)") }
// Class using @Published
let c2 = ex.$progress2.sink { print("$progress2 incomming \($0.fractionCompleted) actual \(ex.progress2.fractionCompleted)") }
// Struct using @Published
let c3 = ex.$progress3.sink { print("$progress3 incomming \($0) actual \(ex.progress3)") }

ex.progress1.completedUnitCount += 1
ex.progress2.completedUnitCount += 1
ex.progress3 = "0.2"

ex.progress1.completedUnitCount += 1
ex.progress2.completedUnitCount += 1
ex.progress3 = "0.4"

/* Outputs (incomming should new value, actual should be old value):
$progress1 incomming 0.0 actual 0.0
$progress2 incomming 0.0 actual 0.0
$progress3 incomming 0.0 actual 0.0

$progress1 incomming 0.2 actual 0.2
// no output from $progress2
$progress3 incomming 0.2 actual 0.0

$progress1 incomming 0.4 actual 0.4
// no output from $progress2
$progress3 incomming 0.4 actual 0.2
*/

ToDo

• Add SwiftLint (by adding xcodeproj: swift package generate-xcodeproj, helps support Xcode Server, too)
• Add Travis CI (without xcodeproj see reddit, medium)
• Add codecov
• Add codebeat
• Add codeclimate
• Add codetriage
• Add jazzy docs
• Add CHANGELOG.md
• Add Carthage support
• Add Cocoapods support

License

PublishedKVO is available under the Apache-2.0 license. See the LICENSE file for more info.

Author

Matis Schotte, dm26f1cab8aa26@ungeord.net

https://github.com/matis-schotte/PublishedKVO