Using a custom DiscreteFormatStyle in Live Activities

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Martin Jr OP

Created Oct ’24

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With iOS 18, Text has a new initializer that takes in a TimeDataSource and a DiscreteFormatStyle.

Similar to this question, I'd like to make a compact timer but can't find a way to do that with any of the system formats.

Since the new API takes in a DiscreteFormatStyle though I figure I could make my own. This works in an app but not in a Live Activity; in Previews it crashes and in the simulator the view looks like placeholder.

Screenshot 2024-10-18 at 2.14.08 PM.png

Are custom format styles not supported in this case? Or might there something wrong with my implementation?

Formatter

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Answer 1

Martin Jr OP

Oct ’24

Update: In the console I get an error that looks like this:

Failed to return view entry from archive for view model with tag jindo-compactTrailing with error: SwiftUI.AnyCodable<SwiftUI.(unknown context at $1d30c3df8).SafelyCodableRequirement>.(unknown context at $1d30caf74).Errors.noType(mangledName: "7SwiftUI18TimeDataFormattingO10ResolvableVy_AA0cD6SourceVAAE15DurationStorageOys0H0V_G23[...]27CompactCountdownFormatStyleVG")

Which I believe either suggests there's some internal requirement my formatter doesn't know about or SwiftUI checks that formatters are of a specific type.

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