使用NSUSerDefaults如何在两次按下按钮时更改颜色

Question

I am new to XCode. I used with NSUserDefaults even though it is not coming what i required means If i click one time on that button it should change the colour to green and if i press it again it should change the colour to black.

Here my Code is -

- (IBAction)subscribeButtonAction:(id)sender {
    if (count == 0) {
        [_subscribeButtonObj setBackgroundColor:[UIColor greenColor]];
        greenStr=[NSString stringWithFormat:@"green"];
        NSUserDefaults *greendefults=[NSUserDefaults standardUserDefaults];
        [greendefults setValue:greenStr forKey:@"greencolor"];
        [greendefults synchronize];
        ///
        count++;
    } else if(count == 1){
        [_subscribeButtonObj setBackgroundColor:[UIColor blueColor]];
        blackStr=[NSString stringWithFormat:@"black"];
        NSUserDefaults *blackDefaults=[NSUserDefaults standardUserDefaults];
        [blackDefaults setValue:blackStr forKey:@"blackcolor"];
        [blackDefaults synchronize];
        //count = 0;
    }
}

In ViewWillAppear I wrote the code like this -

-(void)viewWillAppear:(BOOL)animated
{
    //count = 0;
    if ([[NSUserDefaults standardUserDefaults] stringForKey:@"greencolor"]) {
        NSLog(@"change the button to green color %@",[[NSUserDefaults standardUserDefaults] stringForKey:@"greencolor"]);
    } else {
        NSLog(@"change the button to blackcolor ");
    }
}

Can anyone please help me. Thanks in Advance

Answer 1

There's no need of NSUserDefaults to implement this. Its simple to handle with UIButton 's control states,

• UIControlStateNormal
• UIControlStateSelected

For example,

- (IBAction)changeColor:(id)sender {
    UIButton *button = (UIButton *)sender;
    if (button.selected) { // If selected will change the color into Red
        button.backgroundColor = [UIColor redColor];
        [button setSelected:NO];
    } else {
        button.backgroundColor = [UIColor greenColor];
        [button setSelected:YES];
    }
}

And, keeep in mind you can change your button's state initially like setting this,

[myButton setSelected:YES];

Assign, this code in your viewDidLoad

Cheers!!

Answer 2

If you wanna do it the NSUserDefault way. Setting control states is a nice way though. but It will set a unwanted overlay background to the button if UIControlStateSelected is YES . :

- (IBAction)btnAction:(id)sender {
    NSUserDefaults *color=[NSUserDefaults standardUserDefaults];
    if (count == 0) {
        [self.btnOutlet setBackgroundColor:[UIColor greenColor]];
        [color setValue:@"green" forKey:@"color"];

    }else if(count == 1){
        [self.btnOutlet setBackgroundColor:[UIColor blueColor]];
        [color setValue:@"blue" forKey:@"color"];

    }
    count = !count;
}


- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
    count = 0;

    if([[[NSUserDefaults standardUserDefaults] valueForKey:@"color"] isEqualToString:@"green"]){ // been used
        [self.btnOutlet setBackgroundColor:[UIColor greenColor]];
    }else if([[[NSUserDefaults standardUserDefaults] valueForKey:@"color"] isEqualToString:@"blue"]){
        [self.btnOutlet setBackgroundColor:[UIColor blueColor]];
    }else{ // first time
        [self.btnOutlet setBackgroundColor:[UIColor yellowColor]];
    }
}