//이미지를 중앙 비율을 맞추는것은 contentMode라고 한다//그에대한 자세한 설명은 http://marines.co.kr/archives/174 //contentMode Enum typedef NS_ENUM(NSInteger, UIViewContentMode) { UIViewContentModeScaleToFill, UIViewContentModeScaleAspectFit, // contents scaled to fit with fixed aspect. remainder is transparent UIViewContentModeScaleAspectFill, // contents scaled to fill with fixed aspect. some portion of content may be cl..