Swift中NSWritingDirection导致NSAttributedString崩溃问题求助

Hey there, let's break down why your code is crashing and fix it right away!

崩溃根源 #

The crash happens because of a type mismatch when setting the writingDirection attribute. The NSAttributedStringKey.writingDirection expects an array of integers ([Int]), but you're passing a single integer value directly.

When you combine NSWritingDirection.rightToLeft.rawValue and NSWritingDirectionFormatType.override.rawValue with a bitwise OR, you get a single Int—but the attribute requires this value to be wrapped in an array. This type mismatch triggers an unrecognized selector or type error, leading to the crash.

修正后的代码 #

Here's the fixed version of your code, with the writingDirection value properly wrapped in an array:

let myString = "Swift Attributed String"
let myAttribute = [
    NSAttributedStringKey.foregroundColor: UIColor.blue,
    // Wrap the combined raw value in an array
    NSAttributedStringKey.writingDirection: [NSWritingDirection.rightToLeft.rawValue | NSWritingDirectionFormatType.override.rawValue]
] as [NSAttributedStringKey : Any]
let myAttrString = NSAttributedString(string: myString, attributes: myAttribute)

// Set the attributed text on your label
self.labelUsername.attributedText = myAttrString

额外说明 #

The writingDirection attribute uses an array because it supports handling mixed-direction text (e.g., a string with both left-to-right and right-to-left content). Even if you only need one direction rule, you must wrap the raw value in an array to match the expected type.

内容的提问来源于stack exchange，提问作者Abdullah Umer