Line disappears when drawing with CGContext - objective-c

Question

I am drawing lines in a custom UIView class utilizing drawRect: and CGContext. Everything works fine for the first few lines added but sometimes when I add a new path (ie: CGPoint to CGPoint) to the array of paths to be drawn there is a chance that one of the previously drawn lines will vanish. Why is it vanishing?
- (void)drawRect:(CGRect)rect
{
if ([_paths count]) {
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetStrokeColorWithColor(context, [UIColor darkGrayColor].CGColor);
CGContextSetLineWidth(context, 2.0f);
// Drawing code
for (NSDictionary * path in _paths){
CGPoint startPoint = CGPointMake([path[#"startPointx"] floatValue], [path[#"startPointy"] floatValue]);
CGPoint endPoint = CGPointMake([path[#"endPointX"] floatValue], [path[#"endPointY"] floatValue]);
CGContextMoveToPoint(context, startPoint.x, startPoint.y); //start at this point
CGContextAddLineToPoint(context, endPoint.x, endPoint.y); //draw to this point
}
CGContextStrokePath(context);
}
}
EDIT:
NSMutableDictionary * newPath = [[NSMutableDictionary alloc] init];
newPath[#"startPointx"] = [NSString stringWithFormat:#"%f",startPoint.x];
newPath[#"startPointy"] = [NSString stringWithFormat:#"%f",startPoint.y];
newPath[#"endPointX"] = [NSString stringWithFormat:#"%f",endPoint.x];
newPath[#"endPointY"] = [NSString stringWithFormat:#"%f",endPoint.y];
[_paths addObject:newPath];
---Then remove current _customPathView from superview, instantiate new customPathView and add paths as seen below
[_customPathView setPaths:_paths];
[_scrollContentView insertSubview:_customPathView atIndex:0];
[_customPathView setNeedsDisplay];
It should be noted that I am removing the UIView from it's parent view each time a new path is going to be added to the array and then I instantiate a new UIView with the new paths array just to make sure I'm getting a fresh UIView with all the paths being passed.
See in the images that the line gets drawn first from the purple dot to the gray dot, then to the white dot but when the next line gets drawn from the white dot to the next gray dot the previous line vanishes.

Answer 1

Perhaps you need to set clearsContextBeforeDrawing To NO:
self.clearsContextBeforeDrawing=NO;