If you are developing an iOS or OSX application and did some styling changes at some point, then realize that your cursor is not showing up in the app anymore the issue is most likely related to tint. Tint can be changed per object, or on the whole storyboard itself, and sets the cursor colour. There are three places to check:
Check the control itself, is it set to default of blue? Below you can see its set to default, as it will be in most cases, however it is white. If the default is blue, you may have set it to white or clear. If the default is selected, but is white, try the next step.
The next step. In my scenario I had changed tint globally. This is done through the storyboard. Click anywhere in an open space in the storyboard and look under the file inspector as seen below. This tint will set the default for every object. If it is white, your cursor will be white on a white background for text boxes, which is a bad idea.