Hi, Hugh here.
I have tried a few different apps ... GolfShot, Swing U, Golf GPS and VPAR.
I am currently using an iPhone 6s with these apps and cannot recommend VPAR highly enough. It is by far and away the best of these apps. The GPS feature is very accurate although it does not always get the tee positions correct when switching between Black, Blue and White markers but this deficiency is easily overcome by using the ball position marker on the location of the tee box. It has several excellent features and the scorecard is easy to use.
The only thing I really need is a suitable cradle to hold my iphone on my clicgear 3.5+ cart which does not involve using the umbrella holder as these 2 accessories need to be used in tandem to see the screen clearly when used in sunny conditions. Any suggestions would be most welcome!