[How to adjust contrast of a mask (not the curves itself)]

Tying to get this to work

"You can, however, add a Levels or Curves adjustment to a mask. Add a Curves layer, for instance, and drag it over the Mask thumbnail in the Layers panel so that you get the vertical blue bar. In the Curves dialog box, choose "Alpha" as the channel to be manipulated (rather than the default choice of "Master"). You can directly adjust the mask in this way, and it is effectively a non-destructive layer."

However when I create a mask layer and attach either a curves or level adjustment I see not visible effect to the mask, I would expect to alter the attached curves / level and then view the mask layer by alt-Clicking on it's thumbnail to see the effect of the level/curves.  Am I missing something ?

[Create Selection from Luminance]

@Callum, thanks for taking the time to respond.  For a black and white layer can I not just "load to pixel selection" from one of the RGB channels ?  Also, research has shown this missing feature was identified long ago.  Are there plans to add this capability to the iPad version ?

[Create Selection from Luminance]

Looking to find the "create selection from luminance" (alt-ctrl click on layer thumbnail) on the iPad version of Photo.  Any clues ?

[How to 'View' a Spare Channel]

I am working though the various ways to create Luminosity Masks in Photo, as I work to move my workflow from PS to AP.  After creating my masks and saving them as channels I would like to be able to view each channel -- larger than the thumbnail

So far the best I can do is to create a new pixel layer, load the channel as a component (say red) of the new layer and then create another new layer from the new pixel layer using "Create Greyscale Layer" -- but this is odious.  Any tricks I should know about?

I am thinking it may be useful in the process of generating the masks to keep the orignal layers around but not visible just for reference.   

Part of the process of learning a new tool is to understand the underlying thought process used when the tool was built. In some ways I love AP and what I can do  with it but in some cases -- like Luminosity Masks -- I feel like I am fighting the tool.  If anyone has advice on a better way to do LMs I am all ears.  I am familiar with blend ranges but still do not believe they give me the control I am looking for. 

[Vector Layers Vs Rasterized Vector Layers]

Walt -- you are correct in what you summarized.  Apologies for not being clear but I am working in Photo and did exactly what you indicated

[Vector Layers Vs Rasterized Vector Layers]

Trying to understand the difference between a vector layer and a rasterized vector layer.  I would have suspected that after rasterization I should not be able to adjust the shape -- but I still can.  Is there a good summary of this topic?

[Gradient Tool]

Thanks for the help and the workaround.  Not quite what I was hoping for but it will cut down on the steps I was using.  Given that I am trying to use the gradient as a mask, having an end point of black would be preferred.

[Gradient Tool]

Newbie to the forum but somewhat experienced in post processing.  Using the gradient tool in Affinity Photo to create masks and blends and each time I use the tool it resets the end colors to white and mid-tone grey.  I can reset the colors to what I want (white, black) with no problem but would like to know if there is a way to have my settings recorded so I would not have to reset the colors each time I use the tool.  Hopefully I am missing something simple ?