User can accept a nearby ride offering

[nashirj]

Note: the book button is found only on the Ride Details page Pressing the book button will add this ride to the user's list of rides It also opens the mail app with the email field populated so that the user can message the poster If this ride is already in the user's list of rides or the user is the poster, should show some error

[nashirj]

Here is how to open the mail app: https://stackoverflow.com/questions/25981422/how-to-open-mail-app-from-swift

[nashirj]

Note that mail app doesn't open unless this is run on an actual iPhone

let email = poster?.email
if let url = URL(string: "mailto:\(email)") {
    UIApplication.shared.open(url)
}