CODEWITHSUNDEEP
iosobjective-ccgrect
manujmv
manujmv

Reputation: 6445

Automatically update CGRect based on changing value of CGFloat

I have a variable CGFloat x in my view controller. I created a frame with this variable:

CGRectMake(x,x,4*x,4*x)

When x is changed, I want the value of frame to also change without any manual updating. How can I do that?

Upvotes: 1

Views: 797

Answers (2)

Greg
Greg

Reputation: 9178

There is no way to 'deep copy' a CGFloat, since CGFloat is a primitive type, not an object. Additionally, CGRect is a struct, not an object, so it consists of 4 CGFloats stored one after the other. Not references to CGFloats, but the raw values themselves.

However, if you declare x as a property of your view controller:

@property CGFloat x;

Then you can override the setter of x to update the value of your frame:

- (void)setX:(CGFloat)x {
    _x = x;
    self.myFrame = CGRectMake(x, x, x * 4, x * 4);
}

In this way, every time you change x using self.x = whatever, the setter method will be called and your frame will be updated.

This is basically the safest and most reliable way to do this, as long as you remember to only set x by self.x = whatever, if you set the underlying ivar _x directly, the setter will not be called and the frame won't update.

Upvotes: 3

Dharmbir Singh
Dharmbir Singh

Reputation: 17535

You can't make a copy of Immutable data.So you can't make a copy CGFloat.But if you wanna change your frame in that case you need to set your frame in setter method of X property.

Upvotes: 1

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