CODEWITHSUNDEEP
iosobjective-cnsmutablearrayuibezierpath
user1253528
user1253528

Reputation:

Persisting UIBezierPaths in NSMutableArray

I am trying to draw multiple UIBezierPaths on a custom view, with the ability to manipulate them individually.

path and the NSMutableArray to store the paths are instance variables declared like:

@interface MyCustomView : UIView {  
    UIBezierPath *path;  
    NSMutableArray *paths; // this is initialized in the init method  
}

The path is initialized in touchesBegan as follows:

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event  
{  
    path = [[UIBezierPath alloc] init];  
    [path moveToPoint:[touch locationInView:self];  
}

It is moved in the touchesMoved method as follows:

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event  
{  
    [path addLineToPath:[touch locationInView:self]];  
    [self setsNeedsDisplay];  
}

And I want to store it in the NSMutableArray in touchesEnded:

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event  
{  
    [path closePath];  
    [paths addObject:path];
    [self setNeedsDisplay];  
}

The problem is, after I draw one uibezierpath, and begin to draw one after that, the one i drew first disappears. I'm not sure why this is happening. Thanks in advance!

Note: I know a possible solution is storing all the points of each uibezierpath in a NSMutableArray and redrawing it everytime drawRect is called, but I feel like that is an inefficient implementation.

Upvotes: 0

Views: 787

Answers (2)

DarkDust
DarkDust

Reputation: 92306

You didn't show you drawRect: method, but be aware that in your drawRect:, you need to draw all paths that you want displayed. Every time drawRect: is entered, everything you were drawing before is cleared and has to be drawn again, so just drawing the new one will just give the new one and nothing else.

Upvotes: 1

Divyu
Divyu

Reputation: 1313

This is happening because you are using a global instance path . Instead of using a global instance add your path object to mutable array and get wherever you want.

Try replacing your code something like this.

   @interface MyCustomView : UIView {  
        NSMutableArray *paths; // this is initialized in the init method  
    }

The path is initialized in touchesBegan as follows:

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event  
{  
    UIBezierPath *path = [[UIBezierPath alloc] init];  
    [path moveToPoint:[touch locationInView:self]; 
    [paths addObject:path]; 
}

It is moved in the touchesMoved method as follows:

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event  
{  
    UIBezierPath *path = [paths lastObject];
    [path addLineToPath:[touch locationInView:self]];  
    [self setsNeedsDisplay];  
}

And I want to store it in the NSMutableArray in touchesEnded:

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event  
{  
    UIBezierPath *path = [paths lastObject];
    [path closePath];  
    [self setNeedsDisplay];  
}

Upvotes: 2

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