Swift 5 Playground, .
# 1. as
let array: [Any] = [5, "a", 6]
for case let item as Int in array {
print(item)
}
let array: [Any] = [5, "a", 6]
for item in array.compactMap({ $0 as? Int }) {
print(item)
}
# 3. where is
let array: [Any] = [5, "a", 6]
for item in array where item is Int {
print(item)
}
let array: [Any] = [5, "a", 6]
for item in array.filter({ $0 is Int }) {
print(item)
}