static analyzer issues in UIImage+Resize

[core-code]

OWActivityViewController/UIImage+Resize.m:63:23: warning: Potential leak of an object
CGImageRetain([self CGImage]);
^
OWActivityViewController/UIImage+Resize.m:80:26: warning: Potential leak of an object stored into 'cgImage'
CGImageRef cgImage = CGBitmapContextCreateImage(context);
^
OWActivityViewController/UIImage+Resize.m:93:5: warning: Incorrect decrement of the reference count of an object that is not owned at this point by the caller
CGImageRelease(imgRef);
^~~~~~~~~~~~~~~~~~~~~~
OWActivityViewController/UIImage+Resize.m:103:5: warning: Incorrect decrement of the reference count of an object that is not owned at this point by the caller
CGImageRelease(imgRef);
^~~~~~~~~~~~~~~~~~~~~~
OWActivityViewController/UIImage+Resize.m:115:5: warning: Incorrect decrement of the reference count of an object that is not owned at this point by the caller
CGImageRelease(imgRef);
^~~~~~~~~~~~~~~~~~~~~~
OWActivityViewController/UIImage+Resize.m:127:5: warning: Incorrect decrement of the reference count of an object that is not owned at this point by the caller
CGImageRelease(imgRef);
^~~~~~~~~~~~~~~~~~~~~~
6 warnings generated.