Updated : 2021
How to display / use the grid in Affinity Photo and how to set the grid settings in Affinity Photo tutorial
file
open document
view menu
show grid
The grid can be used for create objects and snapping to a predefined grid. You can use the grid with images and then use that image and grid to create a sketch / drawing / painting (the main reason I use grids in Affinity Photo and it is amazing how many apps do not have this feature so thank you Affinity Photo for including grids in 1.5 etc). You can use the grids to align text and objects and much more in Affinity Photo
view menu
show grid
which then hides the currently displayed grid
View menu
Grid and axis manager
Use automatic grid (to just use the default grid though personally I never like that feature)
show grid set to ON
set spacing to 100px or 600px etc (make certain that the opacity makes the lines visible)
set the divisions to 10 etc (make certain that the opacity for sub divisions allows them to be visible)
set the color of the grid lines
set the color of the subdivision lines
set the opacity for both types of line
Link the color for the lines if required
close
You can set a whole lot more advanced lines for setting up grids for your images by clicking the advanced tab and you can then have
1. standard
2. isometric
3. dimetric
4. oblique
5. trimetric
6. triangular
7. two axis etc
as well as a number of variants such as changing aspect, gutter, angle etc
It should be noted that some of the grid types do not allow for the full range of settings to be used.
Once you have added a grid, you can also use the snapping features included in Affinity Photo
View menu
Grid and axis manager
Make certain the use automatic grid is OFF
Advanced tab
select the 2:1 isometric
Set the spacing
Set the gutter
Set the divisions
Click close
Go to the snapping at the top of Affinity Photo
Enable snapping ON
Make certain the snapping to grid is ON
pen tool in Affinity Photo toolbox
click at the intersections of the grid
Sadly, the grid cannot be turned into an actual grid - hopefully that will be a feature in Affinity Photo 2 ?