In this pr, i do 2 things. The first one, I adapte the swift4 syntax to eliminate the warnings. The second one is performance improvement. Performance improvement as follow, when called dataHolder.setData(data, changeTime: ChangeTime()) method, if method return directly because of the conflict resolution mechanism，and code logic will continue to write data to the cache. In this case, it is unnecessary.
In this pr, i do 2 things. The first one, I adapte the swift4 syntax to eliminate the warnings. The second one is performance improvement. Performance improvement as follow, when called dataHolder.setData(data, changeTime: ChangeTime()) method, if method return directly because of the conflict resolution mechanism，and code logic will continue to write data to the cache. In this case, it is unnecessary.