To convert a .dmg file to .iso on Mac OS is really easy.
Open Terminal and type (if your file is on the desktop):
hdiutil makehybrid -o ~/Desktop/outputFile ~/Desktop/sourceFile.dmg
NB. The outputFile DOES NOT have a file extension, only the source file has the .dmg extension.
This converts the .dmg to an ISO-9660 compatible ISO.
wonderful to see this, i used this into my project open apk file . Thanks for sharing with us.