ios - iOS 画圈

Question

我正在尝试在我的 iOS 应用程序中创建以下圆圈。我知道如何制作圆圈，但不完全确定如何沿着弧线获得点。它必须在代码中而不是图像中。下面也是我目前拥有的代码。

 - (void)drawRect:(CGRect)rect
{
    CGPoint point;
    point.x = self.bounds.origin.x + self.bounds.size.width/2;
    point.y = self.bounds.origin.y + self.bounds.size.height/2;

    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextSetLineWidth(context, 2.0);

    CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor);

    CGRect circle = CGRectMake(point.x/2,point.y-point.x/2,point.x,point.x);

    CGContextAddEllipseInRect(context, circle);

    CGContextStrokePath(context);

    for (int i = 0; i<8; i++) {
        CGRect circleMini = CGRectMake(??????,??????,point.x/4,point.x/4);

        CGContextAddEllipseInRect(context, circleMini);
        CGContextStrokePath(context);
    }

}

更新答案

 float cita = 0;
for (int i = 0; i<8; i++) {

    CGPoint pointCir = CGPointMake(point.x/2 + radius * cos(cita) , (point.y-point.x/2) + radius * sin(cita) );
    CGRect circleMini = CGRectMake(pointCir.x,pointCir.y,radius/4,radius/4);

    CGContextAddEllipseInRect(context, circleMini);
    CGContextStrokePath(context);
    cita += M_PI / 4.0;
}

Answer 1

如果 (x,y) 是圆心，r 是大圆的半径，则第 i 个外圆的圆心将是：

  center(i) = ( x + r * cos(cita) , y + r * sin(cita) )

从 0 开始 cita 并为下一个圆增加 PI/4 弧度（或 45 度）

工作实施

CGFloat cita = 0;
CGFloat bigCircleRadius = point.x / 2.0;
CGFloat smallCircleRadius = bigCircleRadius / 4.0;
for (int i = 0; i < 8; i++) {

    CGPoint smallCircleCenter = CGPointMake(point.x  + bigCircleRadius * cos(cita) - smallCircleRadius/2.0 , point.y + bigCircleRadius * sin(cita) - smallCircleRadius / 2.0 );
    CGRect smallCircleRect = CGRectMake(smallCircleCenter.x,smallCircleCenter.y,smallCircleRadius,smallCircleRadius);

    CGContextAddEllipseInRect(context, smallCircleRect);
    CGContextStrokePath(context);
    cita += M_PI / 4.0;
}

编辑：添加了实现和重命名的变量。

Answer 2

- (void)drawRect:(CGRect)rect
{
    const NSUInteger kNumCircles = 8u;


    CGFloat height = CGRectGetHeight(rect);

    CGFloat smallCircleRadius = height / 10.0f;

    CGRect bigCircleRect = CGRectInset(rect, smallCircleRadius / 2.0f, smallCircleRadius / 2.0f);
    CGFloat bigCircleRadius = CGRectGetHeight(bigCircleRect) / 2.0f;

    CGPoint rectCenter = CGPointMake(CGRectGetMidX(rect), CGRectGetMidY(rect));

    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextSetLineWidth(context, 2.0f);

    CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor);

    CGContextAddEllipseInRect(context, bigCircleRect);

    CGContextStrokePath(context);

    CGFloat alpha = 0;


    for (NSUInteger i = 0; i < kNumCircles; i++)
    {
        CGPoint smallCircleCenter = CGPointMake(rectCenter.x  + bigCircleRadius * cos(alpha) - smallCircleRadius/2.0f , rectCenter.y + bigCircleRadius * sin(alpha) - smallCircleRadius / 2.0f );
        CGRect smallCircleRect = CGRectMake(smallCircleCenter.x,smallCircleCenter.y,smallCircleRadius,smallCircleRadius);

        CGContextAddEllipseInRect(context, smallCircleRect);
        CGContextStrokePath(context);
        alpha += M_PI / (kNumCircles / 2.0f);
    }

}