从枚举类型'enum CGImageAlphaInfo'到不同的枚举类型'CGBitmapinfo'（又名''enum CGBitmapInfo'）的隐式转换

i am converting an old iOS 5 project to iOS6.0 on xCode5 and most of the warnings and errors has been fixed but for this one. any suggestions on how to rewrite the code to avoid the complier warnings.i am converting an old iOS 5 project to iOS6.0