Coastal Morning Glory but then what is it doing in Pretoria? Found in highly disturbed ground next to a soil tip. Doing very well curling up the khaki weed (Alternanthera pungens) and sprawling over the ground. Thought it was I. purpurea to start with but the leaves rule it out. Maybe a garden escape.
https://www.inaturalist.org/observations/191980472
Observation of the spider.