Dynamic property not firing about bond

[srdanrasic]

If will fire if you change its dynFrame property.

If you really need to observe frame changes, you could create a Dynamic from KVO:

class customView:UIView{
   ...

   lazy var frameListener:Bond<CGRect> = Bond<CGRect>(){ [unowned self] frame in
        println("firing :D")
    }

    func bind() {
        dynamicObservableFor(self, keyPath: "frame", defaultValue: CGRectZero) ->| frameListener
    }
}

https://github.com/SwiftBond/Bond#key-value-observing

[whateverx]

Thank you, got it for dynFrame

Using Bond 3.7.2, I was playing with dynamicObservableFor but it throw me an error during the cast of the generic T on this line

public func dynamicObservableFor<T>(object: NSObject, #keyPath: String, #defaultValue: T) -> Dynamic<T> {
...
let value: T = (keyPathValue != nil) ? (keyPathValue as? T)! : defaultValue

Could not cast value of type 'NSConcreteValue' (0x1740576b8) to 'C.CGRect' (0x1002c5f80)

i'll try to find out what is going wrong

[whateverx]

I had to use NSValue for the defaultValue and map to CGRect because object.valueForKeyPath(keyPath)return an NSValue
now it works great !

dynamicObservableFor(self, keyPath: "frame", defaultValue:NSValue(CGRect: CGRectZero)).map{$0.CGRectValue()} ->| frameListener

is there a better way ?

[srdanrasic]

Yeah, that's due to unfortunate differences between ObjC and Swift. There is another way to create Dynamic from KVO property. It allows you to manually convert object. You need to pass two closures. One that converts AnyObject? to CGRect, and one other way round.

dynamicObservableFor(self, keyPath: "frame", from: { $0?.CGRectValue() ?? CGRectZero }, to: { NSValue(CGRect: $0) })

[whateverx]

The second way seems to be better
You've done an amazing job with Swift Bond, thank you!