Am 06.10.2011 um 15:54 schrieb Torsten Curdt:
> Well, if the model is more complex and you bind the view to the model
> you can of course trigger the re-display on the observed changes. But
> what about a simple title property of e.g. a NSButton?
>
> ...and I guess triggering a re-display is not the only use case for
> this "setter extension" - or whatever you want to call it.
I never implement setters/getters for myself. I find it error-prone and it
feels wrong to me.
To give you another example. I use KVO to generate background images
in UIButton
[self addObserver:self forKeyPath:@"color" options:NSKeyValueObservingOptionNew
| NSKeyValueObservingOptionOld | NSKeyValueObservingOptionInitial context:NULL];
[self addObserver:self forKeyPath:@"size" options:NSKeyValueObservingOptionNew
| NSKeyValueObservingOptionOld | NSKeyValueObservingOptionInitial context:NULL];
[self addObserver:self forKeyPath:@"showShadow"
options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld |
NSKeyValueObservingOptionInitial context:NULL];
- (void)observeValueForKeyPath:(NSString *)keyPath
ofObject:(id)object
change:(NSDictionary *)change
context:(void *)context {
if (![change keyValueChanged]) {
return;
}
if([keyPath isEqualToString:@"color"] ||
[keyPath isEqualToString:@"size"] ||
[keyPath isEqualToString:@"showShadow"]) {
[self setBackgroundImage:[HDEButton
backgroundImageForButtonWithColor:self.color size:self.size]
forState:UIControlStateNormal];
[self setBackgroundImage:[HDEButton
backgroundImageForButtonWithColor:HDEGrayBackgroundColor size:self.size]
forState:UIControlStateDisabled];
[...]
Self observing works great for
me._______________________________________________
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