Merge NSObjects

ObjectMerger.swift

protocol ObjectMerger {
    func merge<T>(_ source: T, into dest: T, overwrites: Bool)
}

struct StandartObjectMerger: ObjectMerger {

    func merge<T>(_ source: T, into dest: T, overwrites: Bool) {

        guard let src = source as? NSObject else {
            return
        }

        let classType: AnyClass! = NSClassFromString(src.className)
        var numOfProperties: UInt32 = 0
        let properties = class_copyPropertyList(classType, &numOfProperties)

        for i in 0..<numOfProperties {

            let idx = Int(i)
            let prop = properties![idx]
            let rawAttrs = String(cString: property_getAttributes(prop)!)
            let attrs = Set(rawAttrs.components(separatedBy: ","))
            if attrs.contains("R") {
                continue
            }

            let nsKey = NSString(utf8String: property_getName(prop))!
            let key = nsKey as String
            let newValue = src.value(forKey: key)
            let dst = dest as! NSObject
            if overwrites {
                dst.setValue(newValue, forKey: key)
            } else if newValue != nil {
                dst.setValue(newValue, forKey: key)
            } else {
                //skip nil if not overwrites
            }
        }
    }

}