A simple floating clock for OS X

clock.swift

// The MIT License

// Copyright (c) 2018 Daniel

// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:

// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

// How to build:
// $ swiftc -o clock -gnone -O -target x86_64-apple-macosx10.14 clock.swift
// How to run:
// $ ./clock

import Cocoa

class DraggableView: NSView {
    var initialLocation: NSPoint?

    override func mouseDown(with event: NSEvent) {
        initialLocation = event.locationInWindow
    }

    override func mouseDragged(with event: NSEvent) {
        guard let initialLocation = initialLocation else { return }
        
        let currentLocation = event.locationInWindow
        let offset = NSPoint(x: currentLocation.x - initialLocation.x, y: currentLocation.y - initialLocation.y)

        guard let window = self.window else { return }
        let newOrigin = NSPoint(x: window.frame.origin.x + offset.x, y: window.frame.origin.y + offset.y)
        window.setFrameOrigin(newOrigin)
    }
}

class Clock: NSObject, NSApplicationDelegate {
    var window : NSWindow?

    func applicationDidFinishLaunching(_ aNotification: Notification) {
        let containerView = NSView(frame: NSRect(x: 0, y: 0, width: 170, height: 69))

        let dateLabel = self.initLabel(
            font     : NSFont.monospacedDigitSystemFont(ofSize: 18, weight: .regular),
            format   : "YYYY-MM-dd",
            interval : 10
        )
        containerView.addSubview(dateLabel)

        dateLabel.frame = NSRect(x: 0, y: 46, width: 170, height: 23)

        let timeLabel = self.initLabel(
            font     : NSFont.monospacedDigitSystemFont(ofSize: 36, weight: .regular),
            format   : "HH:mm:ss",
            interval : 1
        )
        containerView.addSubview(timeLabel)
        timeLabel.frame = NSRect(x: 0, y: 0, width: 170, height: 46)

        self.window = self.initWindow(
            rect: NSMakeRect(1145, 428, 170, 69),
            containerView: containerView
        )
    }


    func initLabel(font: NSFont, format: String, interval: TimeInterval) -> NSTextField {
        let formatter = DateFormatter()
        formatter.dateFormat = format

        let label = NSTextField()
        label.font = font
        label.isBezeled = false
        label.isEditable = false
        label.drawsBackground = false
        label.alignment = .center
        label.textColor = NSColor(red: 1, green: 1, blue: 1, alpha: 1-(1/3)*(1/3))

        let timer = Timer.scheduledTimer(withTimeInterval: interval, repeats: true) { _ in
            label.stringValue = formatter.string(from: Date())
        }
        timer.tolerance = interval / 10
        timer.fire()

        return label
    }

    func initWindow(rect: NSRect, containerView: NSView) -> NSWindow {
        let window = NSWindow(
            contentRect : rect,
            styleMask   : .borderless,
            backing     : .buffered,
            defer       : true
        )

        let contentView = DraggableView()
        contentView.frame = rect
        window.contentView = contentView

        contentView.addSubview(containerView)

        window.ignoresMouseEvents = false
        window.level = .floating
        window.collectionBehavior = .canJoinAllSpaces
        window.backgroundColor = NSColor(red: 0, green: 0, blue: 0, alpha: 1/3)
        window.orderFrontRegardless()

        return window
    }
}

let app = NSApplication.shared
let clock = Clock()
app.delegate = clock
app.setActivationPolicy(.accessory)
app.run()