Check if optional array is empty

Updated answer for Swift 3 and above:

Swift 3 has removed the ability to compare optionals with > and <, so some parts of the previous answer are no longer valid.

It is still possible to compare optionals with ==, so the most straightforward way to check if an optional array contains values is:

if array?.isEmpty == false {
    print("There are objects!")
}

Other ways it can be done:

if array?.count ?? 0 > 0 {
    print("There are objects!")
}

if !(array?.isEmpty ?? true) {
    print("There are objects!")
}

if array != nil && !array!.isEmpty {
    print("There are objects!")
}

if array != nil && array!.count > 0 {
    print("There are objects!")
}

if !(array ?? []).isEmpty {
    print("There are objects!")
}

if (array ?? []).count > 0 {
    print("There are objects!")
}

if let array = array, array.count > 0 {
    print("There are objects!")
}

if let array = array, !array.isEmpty {
    print("There are objects!")
}

---

If you want to do something when the array is nil or is empty, you have at least 6 choices:

Option A:

if !(array?.isEmpty == false) {
    print("There are no objects")
}

Option B:

if array == nil || array!.count == 0 {
    print("There are no objects")
}

Option C:

if array == nil || array!.isEmpty {
    print("There are no objects")
}

Option D:

if (array ?? []).isEmpty {
    print("There are no objects")
}

Option E:

if array?.isEmpty ?? true {
    print("There are no objects")
}

Option F:

if (array?.count ?? 0) == 0 {
    print("There are no objects")
}

Option C exactly captures how you described it in English: “I want to do something special only when it is nil or empty.” I would recommend that you use this since it is easy to understand. There is nothing wrong with this, especially since it will “short circuit” and skip the check for empty if the variable is nil.

---

---

Previous answer for Swift 2.x:

You can simply do:

if array?.count > 0 {
    print("There are objects")
} else {
    print("No objects")
}

As @Martin points out in the comments, it uses func ><T : _Comparable>(lhs: T?, rhs: T?) -> Bool which means that the compiler wraps 0 as an Int? so that the comparison can be made with the left hand side which is an Int? because of the optional chaining call.

In a similar way, you could do:

if array?.isEmpty == false {
    print("There are objects")
} else {
    print("No objects")
}

Note: You have to explicitly compare with false here for this to work.

---

If you want to do something when the array is nil or is empty, you have at least 7 choices:

Option A:

if !(array?.count > 0) {
    print("There are no objects")
}

Option B:

if !(array?.isEmpty == false) {
    print("There are no objects")
}

Option C:

if array == nil || array!.count == 0 {
    print("There are no objects")
}

Option D:

if array == nil || array!.isEmpty {
    print("There are no objects")
}

Option E:

if (array ?? []).isEmpty {
    print("There are no objects")
}

Option F:

if array?.isEmpty ?? true {
    print("There are no objects")
}

Option G:

if (array?.count ?? 0) == 0 {
    print("There are no objects")
}

Option D exactly captures how you described it in English: “I want to do something special only when it is nil or empty.” I would recommend that you use this since it is easy to understand. There is nothing wrong with this, especially since it will “short circuit” and skip the check for empty if the variable is nil.