Creating buttons through iteration? - loops

Question

I've been using the Corona engine and I'm trying to create multiple buttons through a loop rather than explicitly creating each individual button. Problem is the loop only seems to be generating one button which suggests it's only iterating once.
Below is what I've got so far...
UPDATED
--> Create Level Selection:
local levelSelectionGroup = display.newGroup( );
--> Level Selected:
local function levelSelected()
print(id);
end
--> Button Creation:
local function createLevelSelection()
local levelsToBeMade = 30; -- Ignore these random numbers for now.
local positionX = 1; -- Ignore again.
local positionY = 1; -- Ignore again.
for buttonNumber=1, levelsToBeMade do
print(buttonNumber);
positionX = (positionX + 10); -- Ignore again.
positionY = (positionY + 10); -- Ignore again.
levelButton[buttonNumber] = widget.newButton{
id = buttonNumber,
label = buttonNumber,
default = "images/levelButton.png",
over = "images/levelButtonPressed.png",
width = 50,
height = 50,
onRelease = levelSelected
}
levelButton[buttonNumber].x = positionX;
levelButton[buttonNumber].y = positionY;
levelSelectionGroup:insert(levelButton[buttonNumber]);
end
end
The console states...
attempt to index global 'levelButton' (a nil value)

Answer 1

I guess you might have a problem with your variables or your scopes. So make sure that levelsToBeMade variable and positionX and positionY variables are correct. If you are absolutely sure, this should work: ( I don't see anything wrong in your code but, for loops are more trustable I guess. )
for i=1, levelsToBeMade do
print( "levelButton+1).." will be created." )
positionX = positionX + 10; -- Ignore numbers.
positionY = postionY + 10; -- Ignore numbers.
levelButton[#levelButton+1] = widget.newButton{
id = #levelButton,
label = #levelButton,
default = "images/levelButton.png",
over = "images/levelButtonPressed.png",
width = 50,
height = 50,
onRelease = levelSelected
}
levelButton[#levelButton].x = positionX;
levelButton[#levelButton].y = positionY;
end
If it doesn't work, just check console and see if the loop is executed desired times.
Last edit:
Oh, didn't notice that. You never created levelButton table before! Before starting to create level buttons you should create that like this: local levelButton = {}, at outside of for loop

Answer 2

You might want to reconsider your algorithm and change this while loop.
If the number of levels to be generated is going to stay constant you might want to do a for loop until the 31 st loop is reached.
for i=1,levelstToBeMade do
levelstToBeMade = (levelsToBeMade - 1); -- Ignore numbers.
positionX = positionX + 10; -- Ignore numbers.
positionY = postionY + 10; -- Ignore numbers.
levelButton[levelsToBeMade] = widget.newButton{
id = levelsToBeMade,
label = levelsToBeMade,
default = "images/levelButton.png",
over = "images/levelButtonPressed.png",
width = 50,
height = 50,
onRelease = levelSelected
}
levelButton[levelsToBeMade].x = positionX;
levelButton[levelsToBeMade].y = positionY;
end
Hope this helps.
Cheers

Answer 3

(Sorry, I don't know Corona so this might not apply.)
What is levelButton, and are you sure it exists? Maybe it should be levelButtons?
If that's fine as it is, then check to make sure newButton() actually returns a table as expected: print(levelButton[buttonNumber])