Replicate block animation ios [UIView animateWithDuration:…]

Question

I would like to replicate something like the built-in UIView class method +animateWithDuration:animations:completion: . So basically I am trying to write a method with a block where I can access/manipulate the inner variables.

Something like this:

int dur = 0.5;

[MyClass changeWithDuration:dur manipulations:^{

    // I want to access these values and change them to the following values
    // in 'dur' seconds, just like the built-in UIView class function does 

    myVariable = 0.5;
    myOtherVariable = 1; 

}];

I would like to use this in a Cocoa application, so using the UIView class method is out of the question.

Answer 1

If you want to access and modify variable you should add __block keyword:

__block int dur = 0.5;

[MyClass changeWithDuration:dur manipulations:^{

    // I want to access these values and change them to the following values
    // in 'dur' seconds, just like the built-in UIView class function does 

    myVariable = 0.5;
    myOtherVariable = 1; 

    //Now you can change value go due variable
    dur = 2.5;

}];

If there is a object you want to access, sometimes you need to create weak reference to that object to avoid retain cycles.

//Extended

If you want to do something similar to UIView animation blocks declare method in .h file:

// This just save typings, you don't have to type every time 'void (^)()', now you have to just type MyBlock
typedef void (^MyBlock)();

@interface MyClass : UIView

-(void)changeWithDuration:(float)dur manipulations:(MyBlock)block;

@end

And in your .m file:

-(void)changeWithDuration:(float)dur manipulations:(MyBlock)block
{
    [UIView beginAnimations:nil context:nil];
    [UIView setAnimationDuration:dur];
    [UIView setAnimationDelay:0.0];
    [UIView setAnimationCurve:UIViewAnimationCurveEaseOut];

    if (block)
        block();

    [UIView commitAnimations];
}

To call the method you can do:

     vi = [[MyView alloc] initWithFrame:CGRectMake(10, 10, 50, 50)];
    [vi setBackgroundColor:[UIColor redColor]];
    [self.view addSubview:vi];
    [vi changeWithDuration:3 manipulations:^{
        vi.frame = CGRectMake(250, 20, 50, 40);
    }];

Is it something you are after?

Answer 2

Okay, it does not seem to be possible...

Duplicate

iOS - Getting a variable from inside a block passed as a parameter