Swift ios date as milliseconds Double or UInt64?

Swift does not allow comparing different types.

seconds is a Double floating point value in seconds with sub-second accuracy.
sampleDate is a UInt64 but the units are not given. sampleDate needs be converted to a Double floating point value with units of seconds.

var sampleDate: Double = Double(sample.getStartDate())

Then they can be compared:

if(sampleDate > cuttDate){}

in iOS it is better to use double, but if you want to easy port your code and keep it consistent you can try this:

func currentTimeMillis() -> Int64{
    let nowDouble = NSDate().timeIntervalSince1970
    return Int64(nowDouble*1000)
}