Written by Paul Hudson @twostraws
If you've ever come across the error message "No 'ceil' candidates produce the expected contextual result type 'Int'" – which can happen with calls to ceil(), floor(), and round() – it's usually down to Swift being unable to satisfy type requirements you have asked for.
Put simply, you might think calling ceil() rounds a floating-point number up to its nearest integer, but actually it doesn't return an integer at all: if you give it a Float it returns a Float, and if you give it a Double it returns a Double.
So, this code works because c ends up being a Double:
let a = 0.5
let c = ceil(a)…whereas this code causes your exact issue because it tries to force a Double into an Int without a typecast:
let c: Int = ceil(a)If you need c to be an integer, the solution is to convert the return value of ceil() to be an integer, like this:
let c = Int(ceil(a))The same is true of the floor() and round() functions, so you'd need the same solution.
Available from iOS 7.0
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