Upgrading to newer features (Sparkle v2.9 backport)

[jozefizso]

Sparkle 2.9 (beta) adds new feature to Appcast feed - the sparkle:minimumUpdateVersion element to specify the minimum bundle version required to update.

<sparkle:minimumUpdateVersion> element

This allows specifying a minimum version the host bundle needs to be on before upgrading. This may be useful for new appcast features where this requirement can be used instead of switching to a new appcast.

Example

This example requires users to be running 1.9 or later to see the update for 2.0:

<item>
    <title>Version 2.0</title>
    <sparkle:version>2.0</sparkle:version>
    <sparkle:minimumUpdateVersion>1.9</sparkle:minimumUpdateVersion>
</item>
<item>
    <title>Version 1.9</title>
    <sparkle:version>1.9</sparkle:version>
</item>