Checking keyDown event.modifierFlags yields error - macos

Question

Im subclassing NSTextView and overriding keyDown. I want to detect command-key-combinations. Command-L, for example.
Apple's documentation indicates that you simply and the modifier flags (in the passed NSEvent) with NSEventModifierFlags.CommandKeyMask.
When I do so:
let ck = NSEventModifierFlags.CommandKeyMask
I receive an odd error:
Binary operator '&' cannot be applied to two 'NSEventModifierFlags' operands.
What's the deal? This is swift 2.0, xcode 7.
Thanks!

Answer 1

Apple's documentation indicates that you simply and the modifier flags
The documentation is still referring to C and Objective-C. Swift uses OptionSetType, which does not use bitwise operators for checking flags.
Instead, use the contains() method to check for one or more flags:
if theEvent.modifierFlags.contains(.CommandKeyMask) {
NSLog("command key down")
}
if theEvent.modifierFlags.contains(.AlternateKeyMask) {
NSLog("option key down")
}
if theEvent.modifierFlags.contains([.CommandKeyMask, .AlternateKeyMask]) {
NSLog("command and option keys down")
}
To check for a single key, use intersect to filter out any unwanted flags, then use == to check for a single flag:
let modifierkeys = theEvent.modifierFlags.intersect(.DeviceIndependentModifierFlagsMask)
if modifierkeys == .CommandKeyMask {
NSLog("Only command key down")
}

Answer 2

NSEventModifierFlags is an optionSet in Swift 2.0. You can use contain method to check it contains the command modifier key
override func keyDown(theEvent:NSEvent) {
if theEvent.characters == "l" && theEvent.modifierFlags.contains(.CommandKeyMask) {
print("command-L pressed")
}
}

Answer 3

I was going to put in a comment, but wasn't able to.
In case someone (like me) comes across this article in the future, Swift has changed a little since 2015.
Swift 4:
theEvent.modifierFlags.contains(.command)
theEvent.modifierFlags.contains(.option)
theEvent.modifierFlags.contains([.command, .option])
NSLog("command and option keys down")
also; (.control) is for CTRL.
This is my particular code:
override func viewDidLoad()
{
super.viewDidLoad()
NSEvent.addLocalMonitorForEvents(matching: NSEvent.EventTypeMask.keyDown, handler: myKeyDownEvent)
}
func myKeyDownEvent(event: NSEvent) -> NSEvent {
if (event.keyCode == 121) && event.modifierFlags.contains([.command, .option]) {
//Do what you want when PGDN + cmd + alt is pressed
}
return event
}