Array extension to remove object by value

As of Swift 2, this can be achieved with a protocol extension method.
removeObject() is defined as a method on all types conforming
to RangeReplaceableCollectionType (in particular on Array) if
the elements of the collection are Equatable:

extension RangeReplaceableCollectionType where Generator.Element : Equatable {

    // Remove first collection element that is equal to the given `object`:
    mutating func removeObject(object : Generator.Element) {
        if let index = self.indexOf(object) {
            self.removeAtIndex(index)
        }
    }
}

Example:

var ar = [1, 2, 3, 2]
ar.removeObject(2)
print(ar) // [1, 3, 2]

Update for Swift 2 / Xcode 7 beta 2: As Airspeed Velocity noticed
in the comments, it is now actually possible to write a method on a generic type that is more restrictive on the template, so the method
could now actually be defined as an extension of Array:

extension Array where Element : Equatable {
    
    // ... same method as above ...
}

The protocol extension still has the advantage of being applicable to
a larger set of types.

Update for Swift 3:

extension Array where Element: Equatable {
    
    // Remove first collection element that is equal to the given `object`:
    mutating func remove(object: Element) {
        if let index = index(of: object) {
            remove(at: index)
        }
    }
}

Update for Swift 5:

extension Array where Element: Equatable {
    
    /// Remove first collection element that is equal to the given `object` or `element`:
    mutating func remove(element: Element) {
        if let index = firstIndex(of: element) {
            remove(at: index)
        }
    }
}