How to create custom modifiers
Updated for Xcode 12.0
If you find yourself constantly attaching the same set of modifiers to a view – e.g., giving it a background color, some padding, a specific font, and so on – then you can avoid duplication by creating a custom view modifier that encapsulates all those changes. So, rather than say “make it red, make it use a large font” and so on, you can just say “make it look like a warning,” and apply a pre-made set of modifiers.
If you want to make your own, define a struct that conforms to the ViewModifier protocol. This protocol requires that you accept a body(content:) method that transforms some sort of content however you want, returning the result.
For example, this creates a new PrimaryLabel modifier that adds padding, a red background, white text, and a large font:
struct PrimaryLabel: ViewModifier {
func body(content: Content) -> some View {
content
.padding()
.background(Color.red)
.foregroundColor(Color.white)
.font(.largeTitle)
}
}To use that in one of your views add the .modifier(PrimaryLabel()) modifier, like this:
struct ContentView: View {
var body: some View {
Text("Hello, SwiftUI")
.modifier(PrimaryLabel())
}
}
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