Use value from UISlider to change another variable? - objective-c

Question

So I'm still learning this Objective C lark and i've hit a stump. All I want to do is use the value from Sliderchanged to populate the 'CGFloat lineWidth =', Hopefully to have the end result of changing the width of the crumbPath line...
******************EDIT*********************
CrumbPathView.h
#import "CrumbPathView.h"
#import "CrumbPath.h"
#import "FirstViewController.h"
#interface CrumbPathView (FileInternal)
- (CGPathRef)newPathForPoints:(MKMapPoint *)points
pointCount:(NSUInteger)pointCount
clipRect:(MKMapRect)mapRect
zoomScale:(MKZoomScale)zoomScale;
#end
#implementation CrumbPathView
-(IBAction)sliderChanged:(UISlider *)sender
{
NSLog(#"slider value = %f", sender.value);
}
- (void)drawMapRect:(MKMapRect)mapRect
zoomScale:(MKZoomScale)zoomScale
inContext:(CGContextRef)context
{
CrumbPath *crumbs = (CrumbPath *)(self.overlay);
CGFloat lineWidth = 30;
// outset the map rect by the line width so that points just outside
// of the currently drawn rect are included in the generated path.
MKMapRect clipRect = MKMapRectInset(mapRect, -lineWidth, -lineWidth);
[crumbs lockForReading];
CGPathRef path = [self newPathForPoints:crumbs.points
pointCount:crumbs.pointCount
clipRect:clipRect
zoomScale:zoomScale];
[crumbs unlockForReading];
if (path != nil)
{
CGContextAddPath(context, path);
CGContextSetRGBStrokeColor(context, 0.0f, 0.0f, 1.0f, 0.5f);
CGContextSetLineJoin(context, kCGLineJoinRound);
CGContextSetLineCap(context, kCGLineCapRound);
CGContextSetLineWidth(context, lineWidth);
CGContextStrokePath(context);
CGPathRelease(path);
}
}
#end
#implementation CrumbPathView (FileInternal)
static BOOL lineIntersectsRect(MKMapPoint p0, MKMapPoint p1, MKMapRect r)
{
double minX = MIN(p0.x, p1.x);
double minY = MIN(p0.y, p1.y);
double maxX = MAX(p0.x, p1.x);
double maxY = MAX(p0.y, p1.y);
MKMapRect r2 = MKMapRectMake(minX, minY, maxX - minX, maxY - minY);
return MKMapRectIntersectsRect(r, r2);
}
#define MIN_POINT_DELTA 5.0
- (CGPathRef)newPathForPoints:(MKMapPoint *)points
pointCount:(NSUInteger)pointCount
clipRect:(MKMapRect)mapRect
zoomScale:(MKZoomScale)zoomScale
{
// The fastest way to draw a path in an MKOverlayView is to simplify the
// geometry for the screen by eliding points that are too close together
// and to omit any line segments that do not intersect the clipping rect.
// While it is possible to just add all the points and let CoreGraphics
// handle clipping and flatness, it is much faster to do it yourself:
//
if (pointCount < 2)
return NULL;
CGMutablePathRef path = NULL;
BOOL needsMove = YES;
#define POW2(a) ((a) * (a))
// Calculate the minimum distance between any two points by figuring out
// how many map points correspond to MIN_POINT_DELTA of screen points
// at the current zoomScale.
double minPointDelta = MIN_POINT_DELTA / zoomScale;
double c2 = POW2(minPointDelta);
MKMapPoint point, lastPoint = points[0];
NSUInteger i;
for (i = 1; i < pointCount - 1; i++)
{
point = points[i];
double a2b2 = POW2(point.x - lastPoint.x) + POW2(point.y - lastPoint.y);
if (a2b2 >= c2) {
if (lineIntersectsRect(point, lastPoint, mapRect))
{
if (!path)
path = CGPathCreateMutable();
if (needsMove)
{
CGPoint lastCGPoint = [self pointForMapPoint:lastPoint];
CGPathMoveToPoint(path, NULL, lastCGPoint.x, lastCGPoint.y);
}
CGPoint cgPoint = [self pointForMapPoint:point];
CGPathAddLineToPoint(path, NULL, cgPoint.x, cgPoint.y);
}
else
{
// discontinuity, lift the pen
needsMove = YES;
}
lastPoint = point;
}
}
#undef POW2
// If the last line segment intersects the mapRect at all, add it unconditionally
point = points[pointCount - 1];
if (lineIntersectsRect(lastPoint, point, mapRect))
{
if (!path)
path = CGPathCreateMutable();
if (needsMove)
{
CGPoint lastCGPoint = [self pointForMapPoint:lastPoint];
CGPathMoveToPoint(path, NULL, lastCGPoint.x, lastCGPoint.y);
}
CGPoint cgPoint = [self pointForMapPoint:point];
CGPathAddLineToPoint(path, NULL, cgPoint.x, cgPoint.y);
}
return path;
}
#end
CrumbPathView.h
#import <MapKit/MapKit.h>
#import <UIKit/UIKit.h>
#interface CrumbPathView : MKOverlayView
{
}
- (IBAction)sliderChanged:(id)sender;
#end
I've added the rest of the code from the .h & .m ...

Answer 1

I think you are mostly there. Your slider is probably stored in a propery...just check it like you would any other property when you need its value.
Example:
-(IBAction)sliderChanged:(UISlider *)sender
{
//[self drawMapRect...]
}
-(void)drawMapRect:(MKMapRect)mapRect zoomScale:(MKZoomScale)zoomScale inContext:CGContextRef)context
{
CrumbPath *crumbs = (CrumbPath *)(self.overlay);
CGFloat lineWidth = self.mySliderControl.value;
//Do something with lineWidth
}

Answer 2

Did you tried this ?
-(IBAction)sliderChanged:(UISlider *)sender
{
NSLog(#"slider value = %f", sender.value);
CrumbPath *crumbs = (CrumbPath *)(self.overlay);
CGFloat lineWidth = (UISlider*)sender.value;
//Set value on crumbpath using slider value
}
- (void)drawMapRect:(MKMapRect)mapRect
zoomScale:(MKZoomScale)zoomScale
inContext:(CGContextRef)context
{
CrumbPath *crumbs = (CrumbPath *)(self.overlay);
}