Context

Hi, I am currently working a lot with SwiftUI and encountered a problem while working with Modifiers. I have this basic setup:

Code

// This TitleView Protocol should be adapted by all SwiftUI Views containing a Title.
protocol TitleView: View {
    var title: String { get set }
}

// This is one of many Views containing a Title, therefore it conforms to the TitleView Protocol.
struct SomeTitleView: TitleView {
    var title: String = "Hello World";

    var body: some View {
        Text(title)
    }
}

// This Extension adds the setTitle Modifier to all Views conforming to TitleView.
extension View where View: TitleView {
    func setTitle(_ title: String) -> some View {
        self.modifier(CRStyleModifier(title: title))
    }
}

// This ViewModifier is supposed to manipulate the Title Property inside Views conforming to TitleView. 
// However, I am not sure how to accomplish it.
struct TextModifier: ViewModifier {
    let title: String
    
    @ViewBuilder func body<Content: TitleView>(content: Content) -> some View {
        content 
        // How can I update the Title Property of the Content?
        // Once I make the body Method generic, I get this error message -> Type 'CRStyleModifier' does not conform to protocol 'ViewModifier'
    }
}

Question

How can I achieve my goal of having a custom Modifier that can modify not just basic things like foregroundColor and font but also more specific ones like title on all Views conforming to a specific protocol? Thanks a lot for your help!

CodePudding user response：

A custom modifier is possible but is not needed in this case as would introduced unneeded complexity, instead your extension can look like

extension View where Self: TitleView {
    func setTitle(_ title: String) -> some View {
        var newView = self
        newView.title = title
        return newView
    }
}

Tested with Xcode 13.3