How to implement custom sequence(for-in container) in Swift

sequence.swift

class HundredContainer: Sequence {
    var count = 0;
    typealias GeneratorType = GeneratorOf<Int>

    func generate() -> GeneratorType {
        return GeneratorOf<Int>({
            if self.count < 100 {
                self.count += 1
                return self.count
            } else {
                return nil;
            }
            })
    }
}

var c = HundredContainer();

for i in c {
    println(i)
}