Synchronize access to `NSObject.lifetime`
Synchronize access to `NSObject.lifetime`

ikesyo/ReactiveCocoa,victorlin/ReactiveCocoa,ohwutup/ReactiveCocoa,sandyway/ReactiveCocoa,calebd/ReactiveCocoa,walkingsmarts/ReactiveCocoa,walkingsmarts/ReactiveCocoa,calebd/ReactiveCocoa,ohwutup/ReactiveCocoa,walkingsmarts/ReactiveCocoa,ReactiveCocoa/ReactiveSwift,sandyway/ReactiveCocoa,ReactiveCocoa/ReactiveSwift,sandyway/ReactiveCocoa,ReactiveCocoa/ReactiveSwift,victorlin/ReactiveCocoa,victorlin/ReactiveCocoa,ohwutup/ReactiveCocoa,calebd/ReactiveCocoa,ikesyo/ReactiveCocoa