No Runtime Error:
func == (l: Car, r: Car) -> Bool { return l.vin == r.vin }
struct Car { let vin: String }
protocol hasDriversLicense: class {
var car: Car? { get set }
}
class YoungPro: hasDriversLicense {
var car: Car? { didSet {
if let oldValue = oldValue, car = car, oldValue == car { return }
print("car changed")
}}
init(){}
}
let you = YoungPro()
you.car = Car(vin: "abc123")Runtime error:
func == (l: Car?, r: Car?) -> Bool {
if l == nil && r == nil { return true }
guard let l = l, let r = r else { return false }
return l.vin == r.vin
}
struct Car { let vin: String } // class, struct, tuple... doesn't matter
protocol hasDriversLicense: class {
var car: Car? { get set }
}
class YoungPro: hasDriversLicense {
var car: Car? { didSet {
if oldValue == car { return }
print("car changed")
}}
init(){}
}
let you = YoungPro()
you.car = Car(vin: "abc123") // EXC_BAD_ACCESS code: 2
Formatted code for bug report: https://bugs.swift.org/browse/SR-2559