Can't change parameter value from pluginInstanceAddedToDocument method

[marinoo3]

Apple Feedback Assistant ID: MISSING

DESCRIBE THE BUG:
I can set the value of a int slider parameter like so:

let paramAPISettings = _apiManager!.api(for: FxParameterSettingAPI_v5.self) as! FxParameterSettingAPI_v5
        
let newToken = Int32.random(in: 1...999999) // generate random token
paramAPISettings.setIntValue(newToken, toParameter: 1, at: CMTime.zero)

However, calling this code in the pluginInstanceAddedToDocument method returns the following error:

Thread 3: Swift runtime failure: Unexpectedly found nil while unwrapping an Optional value

---

TO REPRODUCE:
Create a int slider like so:

func addParameters() throws {
   let paramAPI = _apiManager!.api(for: FxParameterCreationAPI_v5.self) as! FxParameterCreationAPI_v5
   paramAPI.addIntSlider(withName: "token", parameterID: 1, defaultValue: 0, parameterMin: 0, parameterMax: 999999, sliderMin: 0, sliderMax: 999999, delta: 1, parameterFlags: FxParameterFlags(kFxParameterFlag_DEFAULT | kFxParameterFlag_NOT_ANIMATABLE))
}

Programmatically set its value in the pluginInstanceAddedToDocument method:

func pluginInstanceAddedToDocument() {
    let paramAPISettings = _apiManager!.api(for: FxParameterSettingAPI_v5.self) as! FxParameterSettingAPI_v5
        
    let newToken = Int32.random(in: 1...999999) // generate new token
    paramAPISettings.setIntValue(newToken, toParameter: 1, at: CMTime.zero)
}

---

EXPECTED BEHAVIOUR:
From Apple documentation: "The pluginInstanceAddedToDocument is called when a new plug-in instance is created or a document is loaded and an existing instance is deserialized. When the host calls this method, the plug-in is a part of the document and the various API objects work as expected."

Retrieving the value of the parameter works as expected using the FxParameterRetrievalAPI_v6 protocol, I'm wondering why FxParameterSettingAPI_v5.setIntValue doesn't.

I'm quite new to FxPlugs and swift development, maybe I'm missing something.

---

SCREENSHOTS:
N/A

---

SPECS:

• 2021 14-inch MacBook Pro (M1 Max, 32GB RAM, 2TB SSD)
• macOS Sonoma 14.3
• Final Cut Pro 10.7.1
• Motion 5.7

---

ADDITIONAL COMMENTS:
I tried to set the parameter value from a pushbutton event, it worked. The issue occurs when using the pluginInstanceAddedToDocument method.

[latenitefilms]

Great question! I'll try and reproduce and find the answer for you. In the meantime, have you tried wrapping in a FxCustomParameterActionAPI_v4?

let actionAPI = _apiManager!.api(for: FxCustomParameterActionAPI_v4.self) as! FxCustomParameterActionAPI_v4
let time = actionAPI.currentTime


actionAPI.startAction(_:self)
let settingAPI = _apiManager!.api(for: FxParameterSettingAPI_v5.self) as! FxParameterSettingAPI_v5
settingAPI.setCustomParameterValue(myObject, toParameter: myParameterID, at: time)
actionAPI.endAction(_:self)

[belisoful]

There are a few bugs like this in the APIs for FCP. I can confirm this bug in my own experience. I didn't know to report it here. Valid.

[marinoo3]

Great question! I'll try and reproduce and find the answer for you. In the meantime, have you tried wrapping in a FxCustomParameterActionAPI_v4?

let actionAPI = _apiManager!.api(for: FxCustomParameterActionAPI_v4.self) as! FxCustomParameterActionAPI_v4
let time = actionAPI.currentTime


actionAPI.startAction(_:self)
let settingAPI = _apiManager!.api(for: FxParameterSettingAPI_v5.self) as! FxParameterSettingAPI_v5
settingAPI.setCustomParameterValue(myObject, toParameter: myParameterID, at: time)
actionAPI.endAction(_:self)

Thanks for your reply, I tried using a custom parameter and FxCustomParameterActionAPI_v4 as suggested. I got the same error trying to access the setting API. Plus a warning on the console says:

A plugin attempted to call [-FxCustomParameterActionAPI startAction:] at an inappropriate time. Plugins should not call this method when they have been called by the host application.

[marinoo3]

@belisoful did you find a workaround or a a method from which we can call the FxParameterSettingAPI_v5 API? It returns nil everywhere I try...

[latenitefilms]

Someone on the Final Cut Pro team tells me they can't spot any obvious issues in the code, and it's not a known issue. Are you able to upload a very basic sample project with steps to reproduce?

[marinoo3]

Sure, here is a simplified project that highlight the error:
StudioUtility.zip

Simply run the xcode project, launch Motion and try to use the effect in Filters > StudioUtility Group > StudioUtility

In the project you can see that retrieving the parameter value works, while trying to set a new value doesn't as the FxParameterSettingAPI_v5 API returns a nil object

[belisoful]

@belisoful did you find a workaround or a a method from which we can call the FxParameterSettingAPI_v5 API? It returns nil everywhere I try...

No. I didn't. It's why I put that project on hold for FCP 10.7.1.

[marinoo3]

@latenitefilms Any news on the error?

[belisoful]

I have not tested anything in FCP 10.8 yet. Been busy doing edits. :)

ooooo. 10.8.1 is out with bug fixes.... I'll have to check this out.....

[latenitefilms]

I'll test in 10.8.1 and chase up with the Final Cut Pro team.

[marinoo3]

The issue still occurs in Motion 5.8 using FxPlug SDK v4.3...