NSAttributedString gets attributes outside of exception
I am trying to get attributes from an attribute string. Everything is fine if the line is not empty. Take a look:
let s = NSAttributedString(string: "", attributes: [NSForegroundColorAttributeName: UIColor.red])
let range = NSMakeRange(0, s.length)
let attrs = s.attributes(at: 0, longestEffectiveRange: nil, in: range)
Why am I getting an out of bounds exception on the last line?
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This is the expected result. If the string length is 0 (case for ""), it doesn't have a character at index 0, so when you try to access it with s.attributes you should get an out of bounds exception.
Due to indexing starting at 0, index = 0 only exists for String.length> 0.
You can check this easily by using a string of length 1 and entering 1 in s.attributes.
let s = NSAttributedString(string: "a", attributes: [NSForegroundColorAttributeName: UIColor.red])
let range = NSMakeRange(0, s.length)
let attrs = s.attributes(at: 1, longestEffectiveRange: nil, in: range) //also produces out of bounds error
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Since you don't care about longestEffectiveRange, use whichever is attribute(_:at:effectiveRange:)
more efficient.
Both will throw if you call an empty string. This is because the parameter at location:
must be within the string. The docs for it says:
Attention!
Raises the exclusion of the range if the index is outside of the destination symbols.
https://developer.apple.com/reference/foundation/nsattributedstring/1408174-attribute
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