TL; DR: Yes; there's a long history of it, but it was part of upholding white supremacy.
Since the colonial era, the component states that would become South Africa incorporated constables from the communities they sought to control. In some cases, they used more trusted groups (like Fingoes in the Eastern Cape) to provide police for support of magistrates in other areas.
You're talking about apartheid specifically (post-1948), however, and the evolving South African Police Service (and auxiliaries), but the principle is very much the same for Black and other nonwhite populations. In addition to auxiliary Native Police in areas determined to be territories or reserves (later 'homelands') one also had local police in the townships that fed the mines and some factories near cities all over the country. The person in charge of such constables would always be white, but there simply was not enough white manpower to police an entire area themselves; these arrangements tended to be locally handled, not centralized as they would be by the 1960s. Recruiting locally also took advantage of people with an axe to grind, and who might know the social terrain, not to mention could speak the languages; they, in return, escaped from the dangerous work of the mines and got a good paycheck. Of course, the police so hired faced obloquy if they worked in the areas they knew; later, especially in the 1970s and beyond, this would be avoided more actively.
Under apartheid, the development of police forces took a decided turn in 1961 with the creation of the Reserve Police Force under the Act of the same name (not to be confused with the Police Reserve, which was initally wholly white and paramilitary, created in 1972 and operational in 1973). This was a response to militant action by the PAC and ANC, and sought to create and organize volunteer police forces; by 1971, according to Philip Frankel, a quarter of its number were Coloured, black, or Indian. Of course, under Group Areas (Act of 1950 and its amendments) such police could only operate within areas where they resided, even though the command structure ultimately answered to whites.
Frankel refers to criticism from Black commentators that both of these groups were merely sanctioned vigilantes--and some of them no doubt acted exactly that way, emboldened further by the Terrorism Act in 1967 which empowered police to detain any person believed to “endanger the maintenance of law and order” for extended periods (eventually permanently), a measure that led to many deaths in detention. They were also generally resistant to calls to distance themselves from apartheid in the wake of Soweto, for example, a point that Frankel notes as do the informants that Brink et al. interviewed a decade ago. Of course, for many of these police it was their only path of upward mobility and access to opportunity, and once they'd embraced it, letting it go would leave them vulnerable to reprisals AND they'd be no longer privileged within the system that oppressed them.
These were the sort of people the exile Ernest Cole in his House of Bondage photographed checking passes of laborers (sometimes with a white detective right there, as in this mid-1960s image. They operationalized the daily oppression of 'petty' apartheid, the constant reminders that nonwhites and especially Blacks were considered strangers in a white South Africa, which is again ironic given that these same police sought protection within and security from that same regime.
This is all very general, and I apologize if I've left out key elements or developments--I am going off a potent mix of recall and the few articles and books I can reach. I have been looking for statistics on the numbers of police and the staging of their deployment (and the sizes of the 'independent' homeland forces under Grand Apartheid following the Black Local Authorities Act of 1982), but coronavirus restrictions have our library closed. It's worth mentioning that during the era of the Township Wars and the late 1980s push for Ungovernability, many more Black constables were put on SA rolls--41,000 to 85,000 between 1985 and 1990, after a period when actual militarization of law enforcement had cut the numbers of proper police significantly.
One of the works I do not have access to at this moment, but that is extremely important for anyone interested to look at, is J. D. Brewer's Black and Blue: Policing in South Africa (Oxford: OUP, 1994). It is still a very important work despite its age and may include the statistics as well as a discussion of policing as seen from the position of apartheid's impending end.
A few resources:
Elsabé Brink, et al., ed., Soweto 16 June 1976 (2001) - interviews with those involved with movements and actions connected to the Soweto Rising.
Ernest Cole, House of Bondage (1967); see also this remarkable body of photographs, many only discovered in the last few years. Cole was a gifted photographer of the human condition, and as a Black South African was able to capture the banal evil of apartheid on a daily basis, which made House of Bondage a devastating exposé.
Philip H. Frankel, "South Africa: The Politics of Police Control," Comparative Politics 12, no. 4 (1980): 481-99 (which I use for its contemporary discussion; the fact that it lacks a crystal ball into the future but still has seen Soweto and the trends in policing makes it in some ways more useful for particular observations).
Jonny Steinberg, "Policing, State Power, and the Transition from Apartheid to Democracy: A New Perspective," African Affairs 113, no. 451 (2014): 173–91, https://doi.org/10.1093/afraf/adu004 . An interesting retrospect into the South African Police Service as inherited by the postapartheid government.
Again, anyone who knows this in greater detail, please do chime in, especially if you have your actual books to hand and can flesh out or correct my details here. The SAPS during apartheid was a weird thing that embodied the challenges to the idea of policing in a deeply militarized minority-rule ethnostate.