Display an image & hide it according to a variable - lua

Question

I would like to display an image, in a specific area, according to a variable. For example, when the user click on an avatar, it shows an specific image. Once he clicks on other avatar, other image will be displayed.
I've tried to remove the previous image, and display new one, but it said "attempt to call removeself() with a nil value".
Define table in the start :
local item_bigsize = {}
So i tried this :
item[i] = display.newImageRect("items/"..items['pos'..i..'_name']..".png", 80 , 80)
item[i].x = holder_2[i].x+10
item[i].anchorX=0
item[i].y=holder_2[i].y
itemGroup:insert (item[i])
item[i].destination=i
item[i]:addEventListener( "touch", onSwitchPress )
and the function onSwitchPress() works like this :
function onSwitchPress( event )
i=event.target.destination
if (event.phase=="began") then
title_item.text=""
desc_item.text=""
for n=1,3 do
if n~=i then
item_bigsize[n]:removeSelf( )
end
n=n+1
end
elseif (event.phase == "ended") then
item_bigsize[i] = display.newImageRect("items/"..items['pos'..i..'_name']..".png", 240 , 240)
item_bigsize[i].x = 950
item_bigsize[i].anchorX=0
item_bigsize[i].y=display.contentCenterY-130
group:insert (item_bigsize[i])
title_item.text=items['pos'..i..'_title']
desc_item.text=items['pos'..i..'_details']
end
end

Answer 1

Instead of:
if n~=i then
item_bigsize[n]:removeSelf( )
end
Try:
if(n~=i and item_bigsize[n].x~=nil)then --Check whether the object/properties exists
item_bigsize[n]:removeSelf()
end
Keep Coding................ :)

Answer 2

for n=1,3 do
if n~=i then
item_bigsize[n]:removeSelf( )
end
n=n+1
end
First of all why do you increment the value of n manually, the for loop will automatically increments n by 1.So you don't increment it.
So what happens here first time i = 1 and n = 1 the condition fails it will not remove.
second time n increments by and you are manually increments n by 1, so it will become three the condition satisfies because i will 2 be and will enters the loop, it will try to remove the image item_bigsize[3]:removeSelf( )which is not present.
I think this could be the possible error, so remove the n = n+1.
for n=1,3 do
if n~=i then
item_bigsize[n]:removeSelf( )
end
end

Answer 3

You don't have
item_bigsize[i]
Because "i" is not an integer which you want to iterate in "for".

Answer 4

Finally, i've choose to hide/show items as #albert said in previous comment (more simple). I also choose to work with DataBase SQLite3, instead of files because it's faster.
Here is the solution :
function ShowItems( event )
local count = 1
local sql = "SELECT * FROM items WHERE active='oui'"
n=1
number=0
for x in db:urows "select count(*) from items" do
for row in db:nrows(sql) do
item[count] = display.newImageRect("items/"..row.src..".png", 80 , 80)
if n <= 7 then
item[count].x = holder[n].x+10
item[count].y=holder[n].y
elseif n >= 8 and n<15 then
item[count].x = holder_2[n].x+10
item[count].y=holder_2[n].y
elseif n >=15 and n<=21 then
item[count].x = holder_3[n].x+10
item[count].y=holder_3[n].y
end
item[count].anchorX=0
itemGroup:insert (item[count])
item[count].destination=row.id
item[count]:addEventListener( "touch", onSwitchPress )
n=n+1
item_bigsize[count] = display.newImageRect("items/"..row.src..".png", 240 , 240)
item_bigsize[count].x = 950
item_bigsize[count].anchorX=0
item_bigsize[count].y=display.contentCenterY-130
bigimages:insert (item_bigsize[count])
item_bigsize[count].isVisible=false
count = count + 1
end
end
end
and my function to show the "big" size images is :
function onSwitchPress( event )
i=event.target.destination
if (event.phase=="began") then
number = n-1
number_equip = a-1
title_item.text=""
desc_item.text=""
item_bigsize[i].isVisible=true
if n <= 7 then
holder[i].alpha=1
elseif n >= 8 and n<15 then
holder_2[i].alpha=1
elseif n >=15 and n<=21 then
holder_3[i].alpha=1
end
for increment=1,number do
if increment~=i then
if item_bigsize[increment]~= nil then
item_bigsize[increment].isVisible=false
if n <= 7 then
holder[increment].alpha=0.5
elseif n >= 8 and n<15 then
holder_2[increment].alpha=0.5
elseif n >=15 and n<=21 then
holder_3[increment].alpha=0.5
end
--print( increment )
end
end
end
elseif (event.phase == "ended") then
result = "SELECT name,desc FROM items WHERE id ="..i..""
for col1,col2 in db:urows( result ) do
title_item.text=col1
desc_item.text=col2
end
end
end
This solution works very well for me !