preference.swift

struct KeyboardAvoiderPreference: Equatable {
    
    let tag: Int
    let rect: CGRect
    
    static func == (lhs: KeyboardAvoiderPreference, rhs: KeyboardAvoiderPreference) -> Bool {
        print("y: \(lhs.rect.minY) vs \(rhs.rect.minY)")
       return  lhs.tag == rhs.tag && (lhs.rect.minY == rhs.rect.minY)
    }
}

struct KeyboardAvoiderPreferenceKey: PreferenceKey {
    
    typealias Value = [KeyboardAvoiderPreference]
    
    static var defaultValue: [KeyboardAvoiderPreference] = []
    
    static func reduce(value: inout [KeyboardAvoiderPreference], nextValue: () -> [KeyboardAvoiderPreference]) {
         value.append(contentsOf: nextValue())
    }
}