A dropdown selector for layer. Allowed type:

• string: to pick a layer name

• int: to pick a layer number. (use 1 << int to get the mask value)

• LayerMask: to pick a single layer into the LayerMask

• Allow Multiple: No

Note: want a bitmask layer selector? Unity already has it. Just use public LayerMask myLayerMask;

using SaintsField;

[Layer] public string layerString;
[Layer] public int layerInt;

// Unity supports multiple layer selector
public LayerMask myLayerMask;

[Layer]  // But you can enforce a single layer picker instead
public LayerMask singleLayerMask;

It can work with ShowInInspector

[ShowInInspector, Layer] private int layerIntRaw
{
    get => layerInt;
    set => layerInt = value;
}

It can work with ShowInInspector/Button parameters and return value

[ShowInInspector]
private (int i, string s, LayerMask mask) Layer([Layer] int layerI, [Layer] string layerS, [Layer] LayerMask layerMask)
{
    return (layerI, layerS, layerMask);
}

[Button]
private (int i, string s, LayerMask mask) Layer([Layer] int layerI, [Layer] string layerS, [Layer] LayerMask layerMask)
{
    return (layerI, layerS, layerMask);
}