Documenting various things for building macOS apps

• short quick form documentation in a way that makes sense to me - trying to be as heavy with code samples as reasonable for me
• feel free to contribute in a way that is reasonable to you

Swift

Accessibility API

• some official documentation exists but I've had difficulty finding more, so most of how I learned was through searches on GitHub of the things listed in the official documentation
• note that this API exists in objective c as well but the notes below provide syntax in swift

Accessibility Inspector Tool

• hierarchy of UI elements can be explored using the accessibility inspector tool in xcode
• for inspecting menus, open the menu using the accessibility inspector, then refresh using command R, or open the menu, then use option space to toggle the inspector selector

Objects

AXUIElement

• everything is an AXUIElement

Useful Attributes

kAXWindowsAttribute

• if a AXUIElement is an application, this is all the elements that are windows for that application

kAXFocusedUIElementAttribute

• the corresponding AXUIElement that is in focus for the systemwide AXUIElement

kAXChildrenAttribute

• the AXUIElement children of an AXUIElement

Useful Actions

kAXPressAction

• presses the element

kAXShowMenuAction

• shows the menu if there is one

Functions

AXIsProcessTrustedWithOptions(options)

• returns Bool
• options is in the form of a dictionary
• checkOptPrompt as true prompts the user to allow control

AXUIElementCreateApplication(pid)

• returns AXUIElement
• gets the UI element of the application with pid

AXUIElementCreateSystemWide()

• returns AXUIElement
• gets UI element representing entire system

AXUIElementCopyAttributeNames(element, pointer)/AXUIElementCopyActionNames(element, pointer)

• puts all the attribute/action names available for an AXUIElement in the variable at pointer

var names:CFArray? = nil
AXUIElementCopyAttributeNames(element, &names)

AXUIElementCopyAttributeValue(element, attribute, pointer)

• puts all the value for a specified attribute for an AXUIElement in the variable at pointer (ex. kAXFocusedUIElementAttribute)

var focused: CFTypeRef?
AXUIElementCopyAttributeValue(systemWide, kAXFocusedUIElementAttribute as CFString, &focused)

• for values that are certain types (ex. kAXPositionAttribute is a CGPoint), need to use AXValueGetValue

var positionRef: AnyObject?
AXUIElementCopyAttributeValue(focusedWindow!, kAXPositionAttribute as CFString, &positionRef)

var position = CGPoint.zero
AXValueGetValue(positionRef as! AXValue, .cgPoint, &position)

AXUIElementGetPid(element, pointer)

• puts the pid that is managing an AXUIElement in the variable at pointer

var pid: pid_t = 0
AXUIElementGetPid(element as! AXUIElement, &pid)

AXUIElementCopyAttributeValues(element, attribute, index, limit, pointer)

• for attributes that are arrays, puts the attribute values in the variable at pointer
• I've always used index as 0 and limit as 99999
• most used for me for the children attribute

var childrenArray: CFArray?
AXUIElementCopyAttributeValues(element, kAXChildrenAttribute as CFString, 0, 99999, &childrenArray)
var children = (childrenArray as! Array<AXUIElement>)

AXUIElementPerformAction(element, actionType)

• performs an action (ex. press)

AXUIElementPerformAction(element, kAXPressAction as CFString)

AXUIElementIsAttributeSettable(element, attribute, pointer)

• checks if an attribute is settable (ex. focused)

var att: DarwinBoolean = false
AXUIElementIsAttributeSettable(font, kAXFocusedAttribute as CFString, &(att))

AXUIElementSetAttributeValue(element, attribute, value)

• sets an attribute, although the value type is sometimes annoying (ex. focused)

AXUIElementSetAttributeValue(element, kAXFocusedAttribute as CFString, kCFBooleanTrue as CFTypeRef)

AXUIElementSetMessagingTimeout(element, secondsAsFloat)

• used this so main thread isn't blocked whenever trying to do something with accessibility api
• i think no matter what the function will eventually occur, this just limits how long you wait for it to return
• setting a timeout of 0.0 didn't seem to keep it from being blocked but 0.01 was sufficient
• i didnt use this every time i used the accessibility api; i only used it for performing certain actions that were known to be problematic

Global event monitoring

NSEvent approach

Functions

NSEvent.addGlobalMonitorForEvents(matching, handler)

• can't stop events from propagating - because handler has to return void

CGEvent approach

Objects

CGEventMask

• based on bit flags
• for each event you want to listen for (ex. keyDown), take the bitwise OR with (1 << CGEventType.keyDown.rawValue)

var eventMask = (1 << CGEventType.keyDown.rawValue) | (1 << CGEventType.flagsChanged.rawValue)
...
eventMask = eventMask | (1 << CGEventType.leftMouseDown.rawValue) | (1 << CGEventType.rightMouseDown.rawValue) | (1 << CGEventType.otherMouseDown.rawValue)

Functions

CGEvent.tapCreate(location, placement, options, eventMask, callbackFunction, userInfo)

• returns CGEventTap
• placement allows for setting if the callback occurs before or after existing responses
• callback has to be outside of any class and return an optional Unmanaged<CGEvent> type
• I just set userInfo to nil
• then follow up code including enabling the tap

guard let eventTap = CGEvent.tapCreate(tap: .cgSessionEventTap, place: .headInsertEventTap, options: .defaultTap, eventsOfInterest: CGEventMask(eventMask), callback: respondToEvent, userInfo: nil) else {
    print("event tap failed to create")
    exit(1)
}
let loopSource = CFMachPortCreateRunLoopSource(kCFAllocatorDefault, eventTap, 0)
CFRunLoopAddSource(CFRunLoopGetCurrent(), loopSource, .commonModes)
CGEvent.tapEnable(tap: eventTap, enable: true)
CFRunLoopRun()

• in the callback function, return nil stops propagation, while return Unmanaged.passRetained(event) propagates it

CGEvent to NSEvent

let nsEvent = NSEvent.init(cgEvent: event)!

Swift Data Types

Tuples

• access using .#
• create with ()

Visual Elements

Getting rid of the dock icon

• add a row in info.plist
• key: Applicaiton is agent (UIElement)
• type: Boolean
• Value: YES

Delegates

Accessing app delegate elsewhere

• with NSApplication.shared.delegate

objective c

Syntax for functions

Declaring and calling functions with multiple arguments

• argVariableName is what is used within the function
• argName is what is used when calling the function
• function declaration

- (void)funcName:(argType)argVariableName argName:(argType)argVariableName
{

• function call

[self.funcName:argValue argName:argValue];

Calling a function from a parent view controller

if (self.delegate && [self.delegate respondsToSelector:@selector(funcInParent:)]) {
    [self.delegate funcAtParent:argValueIfNeeded];
}

NSDate

Getting and using components

NSDateComponents *components = [[NSCalendar currentCalendar] components:NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear fromDate:date];
// usage: components.year, components.month, components.day

where things are in xcode

Sandbox

• some things require you to not be sandboxing
• remove by clicking the project in project navigator, then the signing and capabilities tab, then clicking the x in the sandbox section

---

If you found this helpful and want to support me, consider sponsoring me via (Venmo)[https://venmo.com/garyshen]/(Paypal)[paypal.me/GaryShen]