The first thing to do when moving to a newer version of Eclipse is to customise it. One of the most useful features of Eclipse is the recommendation of methods, variables etc with the use of keyboard shortcuts. So, when you press the shortcut in your keyboard, all the available methods in the API appear as a list and you can select one of your choice.

Recommendations in eclipse
However in the versions for Mac OS the default shortcut is not very convenient as in windows (ctrl + space). In order to change this or any other shortcut you should do the following:
1. Go to the menu Eclipse -> preferences
2. On the preferences panel select from General, the Keys tab. In this tab you can customise all the keyboard shortcuts
3. The shortcut for recommendations is called “Content Assist”. In order to change the default shortcut, select it from the list and on the Binding field write the combination of your preference as it is shown in the following picture

How to change keyboard shortcuts in eclipse