Draw many lines with Performance - ios

Question

Hey i need a help with building an app. I build an art app, this app is working with interferencies. Thats the reason i need to draw many lines in this app. More lines are better for the interefernces. I think the problem is the iPad can't handle too many lines, because the speed or the performance is too slow.
I don't know how can i speed up my code for more performance on the iPad. Should i use Open GL or something else...
What can i do?
Here are the Draw.m
#import "Draw.h"
#implementation Draw
- (IBAction) sliderValueChanged:(UISlider *)sender {
label.text = [NSString stringWithFormat:#"%f", slider.value];
//NSLog(#"slider value = %f", sender.value);
[self setNeedsDisplay];
}
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
}
return self;
}
- (void)drawRect:(CGRect)rect
{
CGContextRef ctx = UIGraphicsGetCurrentContext();
//NSLog(#"slider value = %f", self.bounds.size.width);
CGMutablePathRef cgpath = CGPathCreateMutable();
CGPathMoveToPoint(cgpath, NULL, 0, 500);
CGMutablePathRef cgpath2 = CGPathCreateMutable();
CGPathMoveToPoint(cgpath2, NULL, 0, 500);
UIBezierPath *uipath = [[UIBezierPath alloc] init];
[uipath moveToPoint:CGPointMake(0, 0)];
int step = 5;
int iterations = self.bounds.size.width/step;
for (int i = 0; i < iterations+1; i++){
//CGPathAddCurveToPoint(cgpath, NULL, 1+i, 0, 1+i, 0, 1+i ,0);
CGPathAddLineToPoint ( cgpath, NULL, 0, 0 );
CGPathAddLineToPoint ( cgpath, NULL, 0, 768 );
CGPathAddLineToPoint ( cgpath, NULL, step*i-slider.value*2, 768 );
CGPathAddLineToPoint ( cgpath, NULL, step*i, 0 );
CGPathAddLineToPoint ( cgpath, NULL, (step*i)+step, 0 );
[[UIColor blackColor] setStroke];
CGContextAddPath(ctx, cgpath);
[self strokeUIBezierPath:uipath];
CGPathRelease(cgpath);
}
- (void)strokeContext:(CGContextRef)context
{
CGContextStrokePath(context);
}
- (void)strokeUIBezierPath:(UIBezierPath*)path
{
[path stroke];
}
#end
image http://img17.imageshack.us/img17/375/53178410200339197475308.jpg

Answer 1

the problem with bezier paths is, that they can be quite 'calculation heavy'.
You could either use straight lines ( CGContextAddLineToPoint(context, point.x, point.y);)
Or you use graphics acceleration.
You could either dive directly into OpenGL or use a game engine to help you with some of the code.
One of the most popular ones ( and as I think quite easy to use ) is cocos2d.

Answer 2

You should be getting better performance using a pattern to fill the screen. There is an entire section with sample code in the Quartz Programming Guide.
In your case you could create a very small pattern cell (height = 1) with just one black pixel to the very left followed by the same number of white pixels as the distance to the next line.