Fixing "Ambiguous reference to member when using ceil or round"
Swift version: 5.6
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.
TAKE YOUR SKILLS TO THE NEXT LEVEL If you like Hacking with Swift, you'll love Hacking with Swift+ – it's my premium service where you can learn advanced Swift and SwiftUI, functional programming, algorithms, and more. Plus it comes with stacks of benefits, including monthly live streams, downloadable projects, a 20% discount on all books, and free gifts!
Sponsor Hacking with Swift and reach the world's largest Swift community!
Available from iOS 7.0
Similar solutions…
- Fixing "Failed to obtain a cell from its DataSource"
- Fixing "Unable to dequeue a cell with identifier"
- Fixing "Class ViewController has no initializers"
About the Swift Knowledge Base
This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.
