The themes of Oswald Mtshali's boy on a swing was focused mainly on the evils and ugliness. Oswald Mtshali’s ‘Boy on a swing’ is a poem that places infernal racial discrimination on a moral slab. In this poem, the poet attempts to open the eyes of the reader to the mental agony that the apartheid system is suffused with, at least from the point of view of black South Africans.

Of course, not that this can be easily inferred from the opening stanza, where we are presented with a boy, oscillating in all innocence, on a swing.

This poem by Mtshali operates as a mouthpiece of the blacks against the oppression of the apartheid regime in a South Africa of the not-too-distant past.
http://mollusco.wordpress.com/2013/01/20/mtshalis-boy-on-a-swing/