Added localization support.
Remove xcuserdata from repo
Already have properties for these
Make validity booleans properties as well
Move ivar definition to implementation block
Use instancetype instead of id
Prefix ivar with underscore
Already have properties for these as well
Use instancetype instead of id
Move ivar definition to implementation block
Prefix ivars with underscore
Method name doesn't need 'and'
Check for nil is unnecessary

Calling -integerValue on nil will return 0
Synthesize by default
Indentation
Defensively copy string
Use 'NO' instead of 'false'
Use cardType property
No need for method prototypes
Use #pragma mark to separate code (instead of comments)