There is no native ios support for something like toast that I am aware of. According to ios Human Interface guidelines the standard convention for addressing temporary messages would be to use the UI Alert. The guidelines go on to suggest the following:
If the alert does this... Informs users of problems they can do nothing about: If the problem isn’t critical, integrate the information into the app’s UI; otherwise, use an alert.
It's my understanding that a UI Alert could be displayed using a pop animation and be automatically dismissed via timeout, to achieve something like toast.
If you require something that looks and behaves a bit more like toast there are a myriad of custom controls you can integrate to achieve the same effect on ios. Here is one for example: