Manual Cocoa Binding - Custom Value Transformer
-
When manually binding a control how can I also bind my custom value
transformer?
I've tried:
NSMutableDictionary *bindingOptions = [NSMutableDictionary dictionary];
[bindingOptions setObject:@"MyCustomValueTransformer"
forKey:@"NSValueTransformerName"];
[myControl bind:@"value" toObject:arrayController
withKeyPath:@"selection.optionValue" options:bindingOptions];
and also:
MyCustomValueTransformer *transformer = [[MyCustomValueTransformer
alloc] init];
NSMutableDictionary *bindingOptions = [NSMutableDictionary dictionary];
[bindingOptions setObject: transformer
forKey:@"NSValueTransformerName"];
[myControl bind:@"value" toObject:arrayController
withKeyPath:@"selection.optionValue" options:bindingOptions];
The error returned for either of these examples is: Cannot find value
transformer with name MyCustomValueTransformer
Has anyone manually bound a control with a custom value transformer and
if so what do I need to do?
Thanks in advance,
Jonathan
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On Jul 16, 2004, at 11:09 PM, Jonathan Younger wrote:> When manually binding a control how can I also bind my custom value<http://homepage.mac.com/mmalc/CocoaExamples/controllers.html>
> transformer?
>> The error returned for either of these examples is: Cannot find value
> transformer with name MyCustomValueTransformer
Have you registered it?
<http://developer.apple.com/documentation/Cocoa/Conceptual/
ValueTransformers/Concepts/Registration.html>
mmalc
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On Jul 16, 2004, at 11:09 PM, Jonathan Younger wrote:> NSMutableDictionary *bindingOptions = [NSMutableDictionary dictionary];
> [bindingOptions setObject: transformer
> forKey:@"NSValueTransformerName"];
> [myControl bind:@"value" toObject:arrayController
> withKeyPath:@"selection.optionValue" options:bindingOptions];
>
> The error returned for either of these examples is: Cannot find value
> transformer with name MyCustomValueTransformer
There are two solutions:
(1) register your value transformer via...
+ (void)setValueTransformer:(NSValueTransformer *)transformer
forName:(NSString *)name;
... on NSValueTransformer....
[NSValueTransformer setValueTransformer: [[[MyCustomValueTransformer
alloc] init] autorelease] forName: @"MyCustomValueTransformer"];
... then pass the name for the NSValueTransformerName option...
NSMutableDictionary *bindingOptions = [NSMutableDictionary dictionary];
[bindingOptions setObject: @"MyCustomValueTransformer"
forKey:@"NSValueTransformerName"];
[myControl bind:@"value" toObject:arrayController
withKeyPath:@"selection.optionValue" options:bindingOptions];
(2) Bind with a specific instance of NSValueTransformer...
MyCustomValueTransformer *valueTransformer =
[[[MyCustomValueTransformer alloc] init] autorelease];
NSMutableDictionary *bindingOptions = [NSMutableDictionary dictionary];
[bindingOptions setObject: valueTransformer
forKey:@"NSValueTransformer"];
[myControl bind:@"value" toObject:arrayController
withKeyPath:@"selection.optionValue" options:bindingOptions];
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> (2) Bind with a specific instance of NSValueTransformer...
>
> MyCustomValueTransformer *valueTransformer =
> [[[MyCustomValueTransformer alloc] init] autorelease];
> NSMutableDictionary *bindingOptions = [NSMutableDictionary dictionary];
> [bindingOptions setObject: valueTransformer
> forKey:@"NSValueTransformer"];
>
> [myControl bind:@"value" toObject:arrayController
> withKeyPath:@"selection.optionValue" options:bindingOptions];
I'm looking for it, but I can't see how this differ's from Jonathan's
second attempt. As an aside, I thought that -dictionary returns an
immutable dictionary even when sent to NSMutableDictionary? Then
again, the error "attempt to modify immutable" doesn't happen, and
I've heard a rumour that some "immutable" instances are really
mutable....
--
Brent Gulanowski
http://www.boredastronaut.com
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On Jul 18, 2004, at 11:09 AM, Brent Gulanowski wrote:> I'm looking for it, but I can't see how this differ's from Jonathan's
> second attempt. As an aside, I thought that -dictionary returns an
> immutable dictionary even when sent to NSMutableDictionary? Then
> again, the error "attempt to modify immutable" doesn't happen, and
> I've heard a rumour that some "immutable" instances are really
> mutable....
The option name is "NSValueTransformer", not "NSValueTransformerName"
as it was in the original version.
+dictionary returns a mutable dictionary when invoked upon
NSMutableDictionary.
Rumors are generally easily dispelled by reading the documentation.
Programming by rumor is generally counterproductive.
b.bum
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