deleting objects if string of object matches string in a separate array - arrays

Question

I have an nsobject class with four strings
class Post: NSObject {
var author: String!
var postID: String!
var pathToImage: String!
var userID: String!
}
I also have a separate class viewcontroller which has a function grabbing posts from firebase. I have an array called posts = [Post](), which is filled by a seperate function going through firebase and grabbing data for each photo. I also have an array called removeArray which is array of strings, which the string is the postID of certain posts. Now this is my problem, I am trying to loop through removeArray, check if the each in removeArray = to the each in posts.postID and check if they are equal. Then either I delete that each in posts.postID post, or I create a new array that is posts - posts with postID's in removeArray. Here is my code now that does not work, it just keeps posts as is.
if posts != nil {
if var array = UserDefaults.standard.object(forKey: "removeArray") as? [String] {
for each in posts {
for one in array {
if one == each.postID {
new.append(each)
}
}
}
return self.posts.count
}
}
So if you have any idea how to take a string in an array, check if that string if eqaul to a string in an array of objects.postID, and remove that object from the array if it is equal. I have tried to research a way to filter it, but so far nothing. Please give me some feedback. Thanks
My problem = http://imgur.com/a/m5CiY

Answer 1

var posts = [p1,p2,p3,p4,p5]
let array = ["aaa","bbb"]
var new:Array<Post> = []
for each in posts {
for one in array {
if one == each.postID {
new.append(each)
}
}
}
print("This objects should be remvoed: \(new)")
posts = Array(Set(posts).subtracting(new))
print("After removing matching objects: \(posts)")

Answer 2

You could use reduce(_:_:)!
class Country {
var name: String!
init(name: String) {
self.name = name
}
}
let countries = [Country(name: "Norway"), Country(name: "Sweden"), Country(name: "Denmark"), Country(name: "Finland"), Country(name: "Iceland")]
let scandinavianCountries = ["Norway", "Sweden", "Denmark"]
// Store the objects you are removing here
var nonScandinavianCountries: [Country]?
let scandinavia = countries.reduce([Country](), {
result, country in
// Assign result to a temporary variable since result is immutable
var temp = result
// This if condition works as a filter between the countries array and the result of the reduce function.
if scandinavianCountries.contains(country.name) {
temp.append(country)
} else {
if nonScandinavianCountries == nil {
// We've reached a point where we need to allocate memory for the nonScandinavianContries array. Instantiate it before we append to it!
nonScandinavianCountries = []
}
nonScandinavianCountries!.append(country)
}
return temp
})
scandinavia.count // 3
nonScandinavianCountries?.count // 2
Resouces:
https://developer.apple.com/reference/swift/array/2298686-reduce