Swift World: Design Patterns — Abstract Factory
Today we will talk about abstract factory pattern. It handles a little more complex use case. As we know, the sedan family has different models like compact, mid-size and full-size.SUV has same categories. Let’s assume we have two factories. One is focused on compact types and the other is on full size. As the following figure tells us, factory A produces compact sedan and compact SUV. Factory B produces full-size sedan and SUV.
Let’s start coding. Here is different sizes of sedans and SUVs. They all conform to respective abstract interface.
protocol Sedan {
func drive()
}class CompactSedan: Sedan {
func drive() {
print("drive a compact sedan")
}
}class MidSizeSedan: Sedan {
func drive() {
print("drive a mid-size sedan")
}
}class FullSizeSedan: Sedan {
func drive() {
print("drive a full-size sedan")
}
}protocol SUV {
func drive()
}class CompactSUV: SUV {
func drive() {
print("drive a compact SUV")
}
}class MidSizeSUV: SUV {
func drive() {
print("drive a mid-size SUV")
}
}class FullSizeSUV: SUV {
func drive() {
print("drive a full-size SUV")
}
}
Then the following is our factories. They all can produce sedan and SUV. A is for compact and B is for full-size.
protocol Factory {
func produceSedan() -> Sedan
func produceSUV() -> SUV
}class FactoryA: Factory {
func produceSedan() -> Sedan{
return CompactSedan()
} func produceSUV() -> SUV {
return CompactSUV()
}
}class FactoryB: Factory {
func produceSedan() -> Sedan {
return FullSizeSedan()
} func produceSUV() -> SUV {
return FullSizeSUV()
}
}
Ok, let’s produce sedan and SUV now.
let factoryA = FactoryA()
let compactSedan = factoryA.produceSedan()
let compactSUV = factoryA.produceSUV()
compactSedan.drive()
compactSUV.drive()let factoryB = FactoryB()
let fullsizeSedan = factoryB.produceSedan()
let fullsizeSUV = factoryB.produceSUV()
fullsizeSedan.drive()
fullsizeSUV.drive()
Another use case is to make different themes for our UI. There are many elements involved in a theme like label, button, background, etc. But in specific theme, each has a style. Please try abstract factory to build this modal.
If you want to learn other creational patterns, we list them here.
