Textures with alpha showing black background when rendered on objects

I have some textures in my Metal app that have areas where the alpha is less than 1, and Metal is putting a black background on the texture when it's mapped to an object in my shader. Totall transparent areas of the texture are black, and semi-transparent areas of the textures look like they're getting blended with the black background rather than what's truly behind them. How do I fix this?