Pedantic Xcode warning fix.
Pedantic Xcode warning fix.

nfarina/calloutview,Suninus/calloutview,XBeg9/calloutview,nfarina/calloutview,Suninus/calloutview,dmiedema/calloutview,Petvetbook/calloutview,Aiwis/calloutview,XBeg9/calloutview,mapbox/SMCalloutView,mapbox/SMCalloutView,Aiwis/calloutview,Petvetbook/calloutview,dmiedema/calloutview