Crash specialized String.imageSize(), - ios

Question

I have a crash in this extension method of String:
func imageSize() -> CGSize {
// self = "https://s3-eu-west-1.amazonaws.com/mimg.haraj.com.sa/userfiles30/2018-8-6/524x334-1_-E7VSb5T20mOouX.jpg"
var width = 0
var height = 0
let split0 = self.split(separator: "/")
if split0.count > 0 {
let split1 = split0.last?.split(separator: "-")
if (split1?.count)! > 0 {
let split2 = split1?.first?.decomposedStringWithCanonicalMapping.split(separator: "x")
width = (split2?.first?.decomposedStringWithCanonicalMapping.toInt())!
if (split2?.count)! > 1 {
// let split2 = split1![1].decomposedStringWithCanonicalMapping.split(separator: "-")
height = (split2?.last?.decomposedStringWithCanonicalMapping.toInt())!
}
}
}
return CGSize(width: width, height: height)
}
The crash is on line return CGSize(width: width, height: height)
I have created an NSString version like this to use the same above method:
#objc extension NSString {
func imageSize1() -> CGSize {
return (self as String).imageSize()
}
}
This is then called from obj-c code:
CGSize imageSize = [url imageSize1];
Examples of url are:
https://s3-eu-west-1.amazonaws.com/mimg.haraj.com.sa/userfiles30/2019-02-07/675x900-1_-CdC62Y2hcV7208.jpg
https://s3-eu-west-1.amazonaws.com/mimg.haraj.com.sa/userfiles30/2019-02-07/675x900-1_-697e3no8ec2E1I.jpg
https://s3-eu-west-1.amazonaws.com/mimg.haraj.com.sa/userfiles30/2019-02-07/675x900-1_-8Af5D20wh9b62z.jpg
What this imageSize() method does is that it parses the image size from the url. The urls above contain the sizes 675x900 -> widthxheight.
In rare case we encounter a url where there is no information of the size and the url is not in the format above. So if the size is not found CGSize = (0 , 0) is returned.
I have tested this method on all expected scenarios.
But due to some reasons the method is causing crashes. May be I missed/messed something.
Here is the link to Crashlytics issue.
Any help would be appreciated.

Answer 1

Try don't use force unwrap !
let exampleString1 = "https://s3-eu-west-1.amazonaws.com/mimg.haraj.com.sa/userfiles30/2018-8-6/524x334-1_-E7VSb5T20mOouX.jpg"
let exampleString2 = "https://s3-eu-west-1.amazonaws.com/mimg.haraj.com.sa/userfiles30/2019-02-07/675x900-1_-697e3no8ec2E1I.jpg"
let exampleString3 = "https://s3-eu-west-1.amazonaws.com/mimg.haraj.com.sa/userfiles30/2019-02-07/675x900-1_-CdC62Y2hcV7208.jpg"
extension String {
func imageSize() -> CGSize? {
// last url component
guard let imageName = self.split(separator: "/").last else { return nil }
guard let imageSizeString = imageName.split(separator: "-").first else { return nil }
let sizes = imageSizeString.split(separator: "x")
guard let first = sizes.first,
let last = sizes.last,
let wight = Int(String(first)),
let height = Int(String(last))
else { return nil }
return CGSize(width: wight, height: height)
}
}
exampleString1.imageSize() // Optional((524.0, 334.0))
exampleString2.imageSize() // Optional((675.0, 900.0))
exampleString3.imageSize() // Optional((675.0, 900.0))
Also try to use guard let and return nil if something wrong. For example Url schema can be changed

Answer 2

The crash is most likely due to force unwrapping optionals. There are several cases in your code where you're using it, which will lead to a runtime error if file name in your URL has a different format than you expect. Try
func imageSize() -> CGSize {
// self = "https://s3-eu-west-1.amazonaws.com/mimg.haraj.com.sa/userfiles30/2018-8-6/524x334-1_-E7VSb5T20mOouX.jpg"
var width = 0
var height = 0
let split0 = self.split(separator: "/")
if let split1 = split0.last?.split(separator: "-")
{
if let split2 = split1.first?.decomposedStringWithCanonicalMapping.split(separator: "x")
{
width = (split2.first?.decomposedStringWithCanonicalMapping.toInt()) ?? 0
if split2.count > 1 {
height = (split2.last?.decomposedStringWithCanonicalMapping.toInt()) ?? 0
}
}
}
return CGSize(width: width, height: height)
}