Issue #617

On macOS 11, we can use .help modifier to add tooltip

Button()
    .help("Click here to open settings")

If you support macOS 10.15, then create empty NSView and use as overlay. Need to updateNSView in case we toggle the state of tooltip

import SwiftUI

struct Tooltip: NSViewRepresentable {
    let tooltip: String

    func makeNSView(context: NSViewRepresentableContext<Tooltip>) -> NSView {
        let view = NSView()
        view.toolTip = tooltip
        return view
    }

    func updateNSView(_ nsView: NSView, context: NSViewRepresentableContext<Tooltip>) {
        nsView.toolTip = tooltip
    }
}


Button(action: self.onGear) {
    Image("gear")
        .styleButton()
}
.overlay(Tooltip(tooltip: "Settings"))
.buttonStyle(BorderlessButtonStyle())

Now we can add tooltip as a background. Before I used to add as overlay but that prevents interaction, even with .disabled(true)

Button(action: self.onGear) {
    Image("gear")
        .styleButton()
       .background(ToolTip(tooltip: "Settings"))
}
.buttonStyle(BorderlessButtonStyle())

And we can even make an extension on View to use tooltip easily

import SwiftUI

@available(iOS 13.0, OSX 10.15, tvOS 13.0, watchOS 6.0, *)
public extension View {
    func toolTip(_ text: String) -> some View {
        return self
            .background(
                ToolTip(text)
            )
    }
}

Button(action: self.onGear) {
    Text("Click here")
}
.toolTip("Show statistics")