饼图Objective-C QuartzCore

Question

我在使用QuartzCore在Objective-C中制作饼图时遇到问题。我不想使用图书馆。它在我的drawPieChart方法中的“for（NSUInteger i = 0; i＆lt; [_sliceArray count]; i ++）”行中一直崩溃并给我一个错误：“exc_bad_access（code = exc_i386_gpflt）”。这是我对PieChart.m文件的全部内容。什么是关于什么的建议？提前谢谢。

#import "PieChart.h"

@implementation PieChart

@synthesize circleRadius = _circleRadius;
@synthesize sliceArray = _sliceArray;
@synthesize colorsArray = _colorsArray;


-(id) initWithFrame:(CGRect)frame {

self = [super initWithFrame:frame];
if (self) {

    //Set up colorSlices
    NSArray *colorSlices = [NSArray arrayWithObjects:[NSNumber numberWithFloat:0.4], [NSNumber numberWithFloat:0.2], [NSNumber numberWithFloat:0.1], [NSNumber numberWithFloat:0.3], nil];

    self.sliceArray = colorSlices;

    //set up the colors for the colorSlices
    NSArray *colors = [NSArray arrayWithObjects:(id)[UIColor orangeColor].CGColor,
                       (id)[UIColor yellowColor].CGColor,
                       (id)[UIColor redColor].CGColor,
                       (id)[UIColor greenColor].CGColor, nil];

    self.colorsArray = colors;

}

return self;
}

-(void)drawRect:(CGRect)rect {

//get the current graphics context so Quartz can draw into it, and pass that context to our drawPieChart method.
   CGContextRef context = UIGraphicsGetCurrentContext();
[self drawPieChart:context];

 }

 - (void)drawPieChart:(CGContextRef)context  {
CGPoint circleCenter = CGPointMake(self.bounds.size.width / 2, self.bounds.size.height / 2);

// Set the radius of your pie chart
self.circleRadius = 100;

for (NSUInteger i = 0; i < [_sliceArray count]; i++) {
    NSLog(@"%lu", i);
    // Determine start angle
    CGFloat startValue = 0;
    for (int k = 0; k < i; k++) {
        startValue += [[_sliceArray objectAtIndex:k] floatValue];
    }
    CGFloat startAngle = startValue * 2 * M_PI - M_PI/2;

    // Determine end angle
    CGFloat endValue = 0;
    for (int j = 0; j >= 0; j--) {
        endValue += [[_sliceArray objectAtIndex:j] integerValue];
    }

    CGFloat endAngle = endValue * 2 * M_PI - M_PI/2;

    CGContextSetFillColorWithColor(context, (CGColorRef)[_colorsArray objectAtIndex:i]);
    CGContextBeginPath(context);
    CGContextMoveToPoint(context, circleCenter.x, circleCenter.y);
    CGContextAddArc(context, circleCenter.x, circleCenter.y, self.circleRadius, startAngle, endAngle, 0);
    CGContextClosePath(context);
    CGContextFillPath(context);
}
}

@end