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respondsToSelector in Swift
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Gerriet M. Denkmann
How to translate this into Swift
- (id)transformedValue:(id)value { if ( ![value respondsToSelector: @selector(doubleValue) ] ) { NSLog(@"%s Error value %@ %@",__FUNCTION__, [value class], value); return @50; }; NSNumber *input = (NSNumber *)value; // maybe NSString double output = … return @(output) } Gerriet.
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Quincey Morris
On Aug 7, 2017, at 09:51 , Gerriet M. Denkmann <g@...> wrote:
It’s not clear which part of that is giving you trouble, but I was able to do this in a playground (Swift 4, Xcode 9), and got the expected output: class A: NSObject print (a.transformedValue (value: NSObject ())) Note that Swift’s “AnyObject” has the same magic behavior as Obj-C’s id, that the compiler will let you call any known method on a receiver variable declared with the type.
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Gerriet M. Denkmann
On 8 Aug 2017, at 00:57, Quincey Morris <quinceymorris@rivergatesoftware.com> wrote:Mostly the #selector. And also, I did not know about AnyObject. This now seems to work: final class SpeedValueTransformer: ValueTransformer { override class func transformedValueClass() -> AnyClass { return NSNumber.self } override func transformedValue(_ value: Any?) -> Any? { let anyValue = value as AnyObject if anyValue.responds(to: #selector (getter: AnyObject.doubleValue)) { let optionalInput = anyValue.doubleValue if let input = optionalInput { let output = input * 3 + 42 return output // NSNumber (value: output) } } return 50 // error case } } Thanks for your help! Kind regards, Gerriet.
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