Apvts - "no default constructor"

[daniel]

The AudioProcessorValueTreeState needs a backlink reference to the AudioProcessor to exist. So you need to supply that as argument, either in the header as default arguments in curly brackets (initialiser list) or in the member constructor list.

You add treeState (*this, undo, "PARAMETER", createParameterLayout()) to the constructor.

Have a look into this thread:

AudioProcessorValueTreeState Improvements

Hello JUCErs We’ve made some changes to the AudioProcessorValueTreeState class: The highlights are: It’s now possible to have an APVTS manage a wide range of different parameter types, including JUCE’s built-in AudioParameterBool, AudioParameterChoice, AudioParameterFloat and AudioParameterInt classes. You can avoid the cumbersome two-stage initialisation process, where you first add parameters and then assign the ValueTree state, with a new constructor that does both operations. To make …