Save UIButton state and load with NSUserDefaults

问题

I was wondering how to detect whether the button was hidden or not, and how much alpha was applied to it. Then, when viewDidLoad is called, these values can be applied to make the buttons the same state they were left in when the application closed.

How can I code this?

Thanks,

James

回答1:

If, as your title suggests, you want to use NSUserDefaults, then you can set them like this:

-(void)saveButtonState:(UIButton*)button {
    NSUserDefaults defaults = [NSUserDefaults standardUserDefaults];
    [defaults setBool:button.hidden forKey:@"isHidden"];
    [defaults setFloat:button.alpha forKey:@"alpha"];
}

-(void)restoreButtonState:(UIButton*)button {
    NSUserDefaults defaults = [NSUserDefaults standardUserDefaults];
    button.hidden = [defaults boolForKey:@"isHidden"];
    button.alpha = [defaults floatForKey:@"alpha"];
}

If you want to do this for multiple buttons, then you can use tags to differentiate between them in the defaults:

-(void)saveButtonState:(UIButton*)button {
    NSUserDefaults defaults = [NSUserDefaults standardUserDefaults];
    [defaults setBool:button.hidden forKey:[NSString stringWithFormat:@"isHidden%d",button.tag]];
    [defaults setFloat:button.alpha forKey:[NSString stringWithFormat:@"alpha%d",button.tag]];
}

-(void)restoreButtonState:(UIButton*)button {
    NSUserDefaults defaults = [NSUserDefaults standardUserDefaults];
    button.hidden = [defaults boolForKey:[NSString stringWithFormat:@"isHidden%d",button.tag]];
    button.alpha = [defaults floatForKey:[NSString stringWithFormat:@"alpha%d",button.tag]];
}

回答2:

To check out the button state, check this post: Xcode: Check if UIButton is hidden, using NSUserDefaults

Regarding the Alpha, try to ask for the return value of: self.button.alpha;

you can update the state (value) of the button and the Alpha button in an SQLite database. In the viewDidLoad method, call back the values from the database and apply them immediately. On how to do this, check out some more info on the web and you'll get there because the internet is filled with tutorials on the topic. Well, that's what I would do, SQLite is really useful actually; but perhaps there are other ways as well.

来源：https://stackoverflow.com/questions/7324689/save-uibutton-state-and-load-with-nsuserdefaults

标签

xcode

uibutton

state

nsuserdefaults

viewdidload