MIN() and MAX() in Swift and converting Int to CGFloat
IosObjective CSwiftIos Problem Overview
I'm getting some errors with the following methods:
-
How do I
return screenHeight / cellCount
as aCGFLoat
for the first method? -
How do I use the equivalent of ObjC's MIN() and MAX() in the second method?
func tableView(tableView: UITableView!, heightForRowAtIndexPath indexPath: NSIndexPath!) -> CGFloat { var cellCount = Int(self.tableView.numberOfRowsInSection(indexPath.section))
return screenHeight / cellCount as CGFloat
}
// #pragma mark - UIScrollViewDelegate
func scrollViewDidScroll(scrollView: UIScrollView) { let height = CGFloat(scrollView.bounds.size.height) let position = CGFloat(MAX(scrollView.contentOffset.y, 0.0))
let percent = CGFloat(MIN(position / height, 1.0)) blurredImageView.alpha = percent
}
Ios Solutions
Solution 1 - Ios
1: You can't downcast from Int to CGFloat. You have to initialize a CGFloat with the Int as input.
return CGFloat(screenHeight) / CGFloat(cellCount)
2: Use the min and max functions defined by the standard library. They're defined as follows:
func min<T : Comparable>(x: T, y: T, rest: T...) -> T
func max<T : Comparable>(x: T, y: T, rest: T...) -> T
Usage is as follows.
let lower = min(17, 42) // 17
let upper = max(17, 42) // 42
Solution 2 - Ios
If you're using Swift 3, max()
and min()
are now called on the sequence (i.e., collection) instead of passing in arguments:
let heights = [5, 6]
let max = heights.max() // -> 6
let min = heights.min() // -> 5
Solution 3 - Ios
You can just use min() and max() - they're built-in.
If you wanted to roll your own (why? - maybe to extend it) you would use something like
func myMin <T : Comparable> (a: T, b: T) -> T {
if a > b {
return b
}
return a
}
Solution 4 - Ios
You need to explicitly convert cellCount
to CGFloat
, since Swift doesn't do automatic type conversion between integers and floats:
return screenHeight / CGFloat(cellCount)
min
and max
functions are defined by the standard library.