Inheriting UIView - Losing instance variables - iphone

Question

Bit of an Objective-C rookie, I've looked around for an answer but haven't been able to find one so forgive me if this is an obvious question.
Basically, I need to draw on the screen segments of a circle (for instance, a 90 degree segment, where a horizontal and vertical line meet at the bottom left and an arc connects the end points). I've managed to achieve this in a custom class called CircleSegment that inherits UIView and overrides drawRect.
My issue is achieving this programatically; I need some way of creating my CircleSegment class and storing in it the desired angle before it draws the segment itself.
Here's what I have so far:
CircleSegment.h
#import <UIKit/UIKit.h>
#interface CircleSegment : UIView {
float angleSize;
UIColor *backColor;
}
-(float)convertDegToRad:(float)degrees;
-(float)convertRadToDeg:(float)radians;
#property (nonatomic) float angleSize;
#property (nonatomic, retain) UIColor *backColor;
#end
CircleSegment.m
#import "CircleSegment.h"
#implementation CircleSegment
#synthesize angleSize;
#synthesize backColor;
// INITIALISATION OVERRIDES
// ------------------------
- (id)initWithFrame:(CGRect)frame {
if ((self = [super initWithFrame:frame])) {
self.opaque = NO;
self.backgroundColor = [UIColor clearColor];
}
return self;
}
- (void)setBackgroundColor:(UIColor *)newBGColor
{
// Ignore.
}
- (void)setOpaque:(BOOL)newIsOpaque
{
// Ignore.
}
// MATH FUNCTIONS
// --------------
// Converts degrees to radians.
-(float)convertDegToRad:(float)degrees {
return degrees * M_PI / 180;
}
// Converts radians to degrees.
-(float)convertRadToDeg:(float)radians {
return radians * 180 / M_PI;
}
// DRAWING CODE
// ------------
- (void)drawRect:(CGRect)rect {
float endAngle = 360 - angleSize;
UIBezierPath* aPath = [UIBezierPath bezierPathWithArcCenter:CGPointMake(100, 100)
radius:100
startAngle:[self convertDegToRad:270]
endAngle:[self convertDegToRad:endAngle]
clockwise:YES];
[aPath addLineToPoint:CGPointMake(100.0, 100.0)];
[aPath closePath];
CGContextRef aRef = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(aRef, backColor.CGColor);
CGContextSaveGState(aRef);
aPath.lineWidth = 1;
[aPath fill];
[aPath stroke];
//CGContextRestoreGState(aRef);
}
- (void)dealloc {
[super dealloc];
}
#end
Note that the .m file is a bit messy with various bits of test code...
So essentially I want to create an instance of CircleSegment, store an angle in the angleSize property, draw a segment based on that angle and then add that view to the main app view to display it...
To try and achieve that, I've add the following test code to viewDidLoad on my ViewController:
CircleSegment *seg1 = [[CircleSegment alloc] init];
seg1.backColor = [UIColor greenColor];
seg1.angleSize = 10;
[self.view addSubview:seg1];
It seems to store the UIColor and angleSize fine when I breakpoint those places, however if I place a breakpoint in drawRect which I overrode on CircleSegment.m, the values have reverted back to nil values (or whatever the correct term would be, feel free to correct me).
I'd really appreciate it if someone could point me in the right direction!
Thanks

Answer 1

It seems to store the UIColor and
angleSize fine when I breakpoint those
places, however if I place a
breakpoint in drawRect which I
overrode on CircleSegment.m, the
values have reverted back to nil
values (or whatever the correct term
would be, feel free to correct me).
Are you sure you are working with the same instance?
Drop in something like NSLog(#"%# %p", NSStringFromSelector(_cmd), self); in viewDidLoad and in drawRect and make sure you are actually dealing with the same instance.
(I've seen cases where a developer will alloc/initWithFrame: a view and then use the instance that was created during NIB loading, wondering why that instance wasn't properly initialized.)

Answer 2

Try using self.angleSize in your DrawRect method (same with backColor). In your test method, replace 10 with 10.0 (to ensure it's setting it as a float).
Also, don't forget to release backColor in your dealloc.