Fixes Value Stored Never Read warning

This commit fixes the following warning: `Value stored to
'saveCallbacks' is never read`
Fix Dereference of Null Pointer warning

This commit fixes the following warning: `Dereference of null pointer
(loaded from variable 'saveCallbacks’)`
Fix Implicit Conversion warning

This commit fixes the following warning: `Implicit conversion loses
integer precision: 'NSUInteger' (aka 'unsigned long') to 'int’`
Merge pull request #27 from sbonami/27-Fix-Xcode-warnings

Fix Xcode warnings