How to get a glow effect in Quartz for the iphone?

I am searching for a glow effect in quartz 2d for the iphone. I tried making lines with different alpha values to simulate glo开发者_运维技巧w but it didn't work...

Can anyone help me with that ??

p.s. I'm making an app where the user can draw with glow. I have the basic lines, but no glow :(

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As far as I know, the Core Animation / Quartz 2D Compositing filters are currently not available in iOS. http://developer.apple.com/iphone/library/documentation/GraphicsImaging/Reference/CALayer_class/Introduction/Introduction.html#//apple_ref/occ/instp/CALayer/compositingFilter, chapter: Special Considerations

But there may be some other ways you could achieve your glow effect using shadows: Adding glowing effect to the circle I hope this helped, kind regards...