Let's see, I can learn Java and get a job building Android apps or a job building web apps or a job writing mainframe software or writing desktop software or writing server software or building web services or making video games...
...or...
I can learn Objective-C and get a job building iOS apps.
If you need a job and you're deciding between the two, Java should be a no-brainer.
Objective-C is a nice tool to have in your toolbox, but it shouldn't be the one you take out the most.