Getting the source
Source is at https://hg.mozilla.org/users/tmielczarek_mozilla.com/gecko-ios/ . The changes are on a bookmark called *ios*. I am doing local development using changeset evolution, so be warned that the changesets in that repository will change over time.
To clone the repo:
hg clone https://hg.mozilla.org/users/tmielczarek_mozilla.com/gecko-ios/ hg up ios
To pull the repo into an existing clone:
hg pull -B ios https://hg.mozilla.org/users/tmielczarek_mozilla.com/gecko-ios/ hg up ios
n.b.: Due to weirdness with how our Mercurial sync works the bookmark may not be correct. You may have to just hg pull all the changesets and hg up to the latest changeset, which is currently 01ac51db4f07.
There are mozconfigs to use in the tree under build/. Use iphone-simulator-mozconfig to build for the simulator and iphone-device-debug-mozconfig to build for device. You also need to build an embedding app using XCode.
First, build Gecko:
export MOZCONFIG=`pwd`/build/iphone-simulator-mozconfig # or export MOZCONFIG=`pwd`/build/iphone-device-debug-mozconfig ./mach build
embedding/ios/GeckoEmbed/GeckoEmbed.xcodeproj in XCode. Change the target to some variant of the iOS simulator (click on the GeckoEmbed icon just beside the play and stop buttons), then select Product -> Build For -> Running. You should then be able to do Product -> Run if the build was successful, and the simulator should open eventually showing mozilla.org. To build for device select iPhone from that menu and follow the same steps.
The XCode project has an external build step to rebuild Gecko using
make binaries, so once you've done a full Gecko build you can edit and rebuild from XCode.