Best way to bind custom NSView with custom NSObject

Question

I'm trying to bind a property from a custom NSView to another on a custom NSObject. Both properties are simple bool value.

As a newbie with custom binding i've read Apple Documentation and searched on stackoverflow.

So I created a custom NSView and a custom NSObject, added a bool property called 'enabled' to both and bind them with [myCustomView bind:@"enabled" toObject:myObject withKeyPath:@"enabled" options:nil];

My customView use the approach explained in this article http://www.tomdalling.com/blog/cocoa/implementing-your-own-cocoa-bindings/ to notify value's changes and prevent memory retain issues.

I started my app, it works ! Wonderful ... but it's only one way binding ! When I click my customView, the custom object's property is updated (right) but if the custom object's property value change, my custom view's property isn't updated (Grrrr)

I'm a bit confused because as far as i understood custom bindings, Apple recommendation is to manually implement bind:toObject:withKeyPath:options and register an observer to track property's value changes and Tom Dalling's approach says the opposite.

So what is the best way to bind my properties in a bi-directional way ?

"I've heard of two ways of doing something. I tried one of them and it didn't work. Now I'm all out of ideas!" — Ken Thomases, May 07 '16 at 20:07
Do you change the value of your custom object's property in a KVO compliant way? — Willeke, May 08 '16 at 01:15
What do you mean by change the value of property in a kvo compliant way ? By registering an observer ? — miosepayo, May 08 '16 at 06:29
How do you change the value of your custom object's property? — Willeke, May 08 '16 at 20:57
I simply assign a new value for my customObject's property. `customObject.enabled = value` I also tried this syntax `[customObject setValue:[NSNumber numberWithBool:value] forKey:@"enabled"];` but it doesn't work. — miosepayo, May 09 '16 at 06:54

score 0 · Answer 1 · edited May 23 '17 at 11:52

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This SO answer here indicates that you just setup a symmetric binding going the other way. I haven't tried this, but it sounds like the following will work.

[myObject bind:@"enabled" toObject:myCustomView withKeyPath:@"enabled" options:nil];

edited May 23 '17 at 11:52

Community

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answered May 08 '16 at 00:26

Daniel Wabyick

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I've already tried to setup the symmetric binding but it doesn't work. – miosepayo May 08 '16 at 06:27

score 0 · Answer 2 · answered May 09 '16 at 22:30

I'm a bit confused because as far as i understood custom bindings, Apple recommendation is to manually implement bind:toObject:withKeyPath:options and register an observer to track property's value changes and Tom Dalling's approach says the opposite.

You have to implement both. You have to observe myObject with keypath @"enabled" so when myObject.enabled changes you can change myCustomView.enabled. You have to set myObject.enabled when myCustomView.enabled changes.

See Responding to Changes

Best way to bind custom NSView with custom NSObject

2 Answers2