timer.performWithDelay()

Type Function
Library timer.*
Return value Table
Revision Release 2021.3642
Keywords timer, delay, performWithDelay
See also timer
timer.pause()
timer.cancel()

Overview

Calls a specified function after a delay. This function returns a table that can be used with other timer functions. For example, the returned table can be passed to timer.cancel() to cancel the invocation of the specified listener.

Gotchas

Timers will be automatically paused when the application is suspended and resume when the application is resumed. However, to avoid unwanted behaviours, it is strongly advised to handle your timers manually. Thus, if you have running timers that are not paused and resumed (in code) upon suspension of the app, you should handle this task by calling timer.pause() and timer.resume() on all applicable timers.

Timers will not be automatically cancelled when changing a scene. Thus, if you have running timers that are not cancelled, you must handle this manually by calling timer.cancel() on all applicable timers.

Syntax

timer.performWithDelay( delay, listener [, iterations] [, tag] )
delay (required)

Number. The delay in milliseconds, for example, 1000 = 1 second. Note that timers cannot execute faster than the runtime framerate of the app. For example, if the framerate of the app is 60 frames per second, as defined in the config.lua file (guide), the shortest delay for a timer is approximately 16.667 milliseconds (1000/60 = ~16.667).

listener (required)

Listener. The listener to invoke after the delay. This may be either a function listener or a table listener. If a table listener, it must have a timer method because timer events are sent to the listener.

iterations (optional)

Number. Optionally specify the number of times listener is to be invoked. By default, it is 1; pass 0 or -1 if you want the timer to loop forever.

tag (optional)

String. Optionally assign a tag to the timer. You can pause, resume or cancel all timers that share the same tag with a single function call. Note: Using tag requires Solar2D 2020.3611 or a newer build.

Examples

Function Listener
local function listener( event )
    print( "listener called" )
end
 
timer.performWithDelay( 1000, listener )
Table Listener
local listener = {}
function listener:timer( event )
    print( "listener called" )
end
 
timer.performWithDelay( 1000, listener )
Passing Parameters (1)
-- Lua closure method

local function spawnBall( randomPosition )
    ballPosition = display.newCircle( 100, 100, 20 )
    ballPosition.x = randomPosition
end

-- Obtain a random number for the spawned object's x position
local randomPosition = 100 + math.random(200)

-- Wrap "spawnBall" and "randomPosition" inside a closure
local myClosure = function() return spawnBall( randomPosition ) end
timer.performWithDelay( 2000, myClosure, 1 )
Passing Parameters (2)
-- Variable handle method

local function onTimer( event )
    -- Access "params" table by pointing to "event.source" (the timer handle)
    local params = event.source.params
    print( params.myParam1 )
    print( params.myParam2 )
end

-- Assign the timer to a variable "tm"
local tm = timer.performWithDelay( 1000, onTimer )
-- Assign a table of parameters to the "tm" handle
tm.params = { myParam1 = "Parameter1", myParam2 = "Parameter2" }

Extras

If you want to add new functionality or modify existing ones, you can download or fork the source code from GitHub and include in your project(See Using External Modules).