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swiftjavascriptcore

Create JSStringRef in Swift

I'm using the new (i.e., Objective-C) JavaScriptCore API in Swift. However, JSContext's evaluateScript method doesn't support the source URL and starting line number parameters that JSEvaluateScript (from the C API) does, so I'm trying to call the C method from my Swift code.

The C method takes JSStringRefs instead of Strings, so I need to create those. When I try the obvious solution:

println(JSStringCreateWithCFString("an example").takeRetainedValue())

I get an EXC_BAD_ACCESS (code=EXC_I386_GPFLT). (I'm using takeRetainedValue() because the documentation notes that JSStringCreateWithCFString follows the Create Rule, but takeUnretainedValue() gives me the same error). What am I doing wrong?

Solution

  • This was a bug in the Swift header for JavaScriptCore. The correct code would now be, for example:

    import JavaScriptCore

let str = JSStringCreateWithCFString("an example")
let len = JSStringGetLength(str)
JSStringRelease(str)