10.13核心绘图（一）

- (void)drawRect:(CGRect)rect {
    
    // 拿到当前的图形上下文
    CGContextRef ref = UIGraphicsGetCurrentContext();
   
    // 拼接路径并且放到图形上下文
    CGContextMoveToPoint(ref, 100, 100);
   
    CGContextAddLineToPoint(ref, 150, 150);
   
    CGContextStrokePath(ref);
    
}

    // OC方法，贝塞尔曲线
    UIBezierPath *path = [UIBezierPath bezierPath];
   
    [path moveToPoint:CGPointMake(10, 10)];
   
    [path addLineToPoint:CGPointMake(100, 100)];
   
    [path stroke];

- (void)test4
{
    // 画弧
    //        UIBezierPath* path = [UIBezierPath bezierPathWithArcCenter:CGPointMake(150, 150) radius:100 startAngle:0 endAngle:M_PI_4 clockwise:YES];
    //
    //        [path stroke];

    CGContextRef ctx = UIGraphicsGetCurrentContext();

    CGContextAddArc(ctx, 150, 150, 100, 0, M_PI_4, 1);

    CGContextStrokePath(ctx);
}

- (void)test3
{
    // 椭圆
    //    [[UIBezierPath bezierPathWithOvalInRect:CGRectMake(100, 100, 200, 100)] stroke];

    CGContextRef ctx = UIGraphicsGetCurrentContext();

    CGContextAddEllipseInRect(ctx, CGRectMake(100, 100, 100, 200));

    CGContextStrokePath(ctx);
}

- (void)test2
{
    // 圆角矩形
    [[UIBezierPath bezierPathWithRoundedRect:CGRectMake(100, 100, 100, 100) cornerRadius:50] stroke];
}

- (void)test1
{
    // 矩形
    UIBezierPath* path = [UIBezierPath bezierPathWithRect:CGRectMake(100, 100, 100, 100)];
    [path stroke];
}

// 饼状图
- (void)drawRect:(CGRect)rect {
   
    // 模拟服务器传过来要绘制的一组数据
    NSArray *array = @[@0.1,@0.3,@0.2,@0.4];
    CGFloat start = 0;
    CGFloat end = 0;
   
    for (int i = 0; i< array.count; i++) {
       
        end =  2 * M_PI * [array[i] floatValue] + end;
       
        // 画弧
        UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:CGPointMake(150, 150) radius:80 startAngle:start
                                     endAngle:end clockwise:true];
        // 弧链接圆心变成披萨
        [path addLineToPoint:CGPointMake(150, 150)];
       
        // 随机颜色
        [[self randomColor] setFill];
       
        // 填充
        [path fill];
        start = end;
    }
 
}

// 随机颜色
- (UIColor *)randomColor {
    CGFloat randR = arc4random() % 255/256.0;
    CGFloat randG = arc4random() % 255/256.0;
    CGFloat randB = arc4random() % 255/256.0;
   
    return [UIColor colorWithRed:randR green:randG blue:randB alpha:1.0];
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
   
    [self setNeedsDisplay];
}