You can clone with
iOS 4 still has quite a lot of market share. Currently it will crash on iOS 4 with exception:
dyld: Symbol not found: OBJC_CLASS$_NSJSONSerialization
Is it possible to use an old JSON framework fo IOS 4 devices? such as SBJson?
Here is some reference for possible JSON frameworks:http://stackoverflow.com/questions/8342411/getting-dyld-symbol-not-found-objc-class-nsjsonserialization-on-ios4
There are other iOS 5 dependencies. One small but crucial one means that the NSURLProtocol implementation that makes TouchDB able to talk to CouchCocoa won't be possible on iOS 4. You're welcome to try to get everything working on iOS 4, but it's more work than you imagined...
Is this issue still worth fixing? iOS4 market share isn't what it was 8 months ago and it sounds like it may be more trouble than it's worth to get TouchDB up to feature parity on iOS4
You're probably right; I would guess iOS 4 has pretty minimal market share now. Also, there have been other changes that might make supporting it more difficult. Does iOS 4 even support ARC at all?
Probably best to close this, as I can't see it becoming enough of a priority to actually work on.