Removing objects from an array based on another array

Question

I have two arrays like this:

var arrayA = ["Mike", "James", "Stacey", "Steve"] var arrayB = ["Steve", "Gemma", "James", "Lucy"] 

As you can see, James and Steve match and I want to be able to remove them from arrayA. How would I write this?

Answer 1

@francesco-vadicamo's answer in Swift 2/3/4+

 arrayA = arrayA.filter { !arrayB.contains($0) } 

Answer 2

The easiest way is by using the new Set container (added in Swift 1.2 / Xcode 6.3):

var setA = Set(arrayA) var setB = Set(arrayB)  // Return a set with all values contained in both A and B let intersection = setA.intersect(setB)   // Return a set with all values in A which are not contained in B let diff = setA.subtract(setB) 

If you want to reassign the resulting set to arrayA, simply create a new instance using the copy constructor and assign it to arrayA:

arrayA = Array(intersection) 

The downside is that you have to create 2 new data sets. Note that intersect doesn't mutate the instance it is invoked in, it just returns a new set.

There are similar methods to add, subtract, etc., you can take a look at them