快速上手UIBezierPath

UIBezierPath主要用来绘制矢量图形，它是基于Core Graphics对CGPathRef数据类型和path绘图属性的一个封装，所以是需要图形上下文的（CGContextRef），所以一般UIBezierPath在drawRect中使用。

使用方法

UIBezierPath 是对 CGPathRef 的封装。创建矢量图形时，拆解成一或多条线段，拼接起来，每条线段的终点都是下一条线段的起点。

具体地：

1.创建一个 UIBezierPath 对象

2.用 moveToPoint: 设置初始线段的起点

3.添加线段，定义一或多个子路径

4.修改 UIBezierPath 的绘图相关的属性，比如stroke path的属性 lineWidth 和 lineJoinStyle ，filled path的属性 usesEvenOddFillRule

注意:如果是矩形或者圆之类的特殊图形，可以不用第2步。

代码案例

• 画直线

    UIBezierPath *path = [UIBezierPath bezierPath];

    [path moveToPoint:CGPointMake(50, 50)];
    [path addLineToPoint:CGPointMake(100, 50)];

    path.lineWidth = 5.0f;
    path.lineJoinStyle = kCGLineJoinRound;

    [path stroke];

• 创建三角形

    UIBezierPath *path = [UIBezierPath bezierPath];

    [path moveToPoint:CGPointMake(50, 50)];
    [path addLineToPoint:CGPointMake(300, 50)];
    [path addLineToPoint:CGPointMake(200, 150)];

    // 最后的闭合线是可以通过调用closePath方法来自动生成的，也可以调用-addLineToPoint:方法来添加
    //  [path addLineToPoint:CGPointMake(50, 50)];

    [path closePath];

    path.lineWidth = 5.0f;

    [path stroke];

• 创建矩形

    UIBezierPath *path = [UIBezierPath bezierPathWithRect:CGRectMake(50, 100, 50, 50)];

    path.lineWidth = 5.0f;

    [path stroke];

• 创建内切曲线

    UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(50, 200, 50, 50)];

    path.lineWidth = 5.0f;

    [path stroke];

    UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(50, 200, 50, 100)];

    path.lineWidth = 5.0f;

    [path stroke];

• 创建带有圆角的矩形，当矩形变成正圆的时候，Radius就不再起作用

    UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(50, 300, 50, 50) cornerRadius:15.0f];

    path.lineWidth = 5.0f;

    [path stroke];

• 设定特定的角为圆角的矩形

    UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(50, 400, 50, 50) byRoundingCorners:UIRectCornerBottomLeft cornerRadii:CGSizeMake(5,5)];

    path.lineWidth = 5.0f;

    [path stroke];

• 创建圆弧

    UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:CGPointMake(100, 550) radius:25 startAngle:0 endAngle:1.5*M_PI clockwise:YES];

    path.lineWidth = 5.0f;

    [path stroke];

• 通过路径A创建路径B

    UIBezierPath *path_A = [UIBezierPath bezierPath];

    [path_A moveToPoint:CGPointMake(200, 50)];

    [path_A addLineToPoint:CGPointMake(250, 100)];

    path_A.lineWidth = 5.0f;

    UIBezierPath *path_B = [UIBezierPath bezierPathWithCGPath:path_A.CGPath];

    [path_B stroke];

• 创建三次贝塞尔曲线

    UIBezierPath *path = [UIBezierPath bezierPath];

    [path moveToPoint:CGPointMake(100, 200)];

    [path addCurveToPoint:CGPointMake(300, 200) controlPoint1:CGPointMake(150, 150) controlPoint2:CGPointMake(250, 250)];

    [path stroke];

• 创建二次贝塞尔曲线

    UIBezierPath *path = [UIBezierPath bezierPath];

    [path moveToPoint:CGPointMake(100, 200)];

    [path addQuadCurveToPoint:CGPointMake(300, 200) controlPoint:CGPointMake(150, 150)];

    [path stroke];

• 添加圆弧

    UIBezierPath *path = [UIBezierPath bezierPath];

    [path moveToPoint:CGPointMake(200, 400)];
    [path addLineToPoint:CGPointMake(225, 410)];

    [path addArcWithCenter:CGPointMake(200, 400) radius:25 startAngle:0 endAngle:1.5*M_PI clockwise:YES];

//    [path closePath];
//    [path removeAllPoints];

    [path stroke];

• 追加路径

    UIBezierPath *path_A = [UIBezierPath bezierPath];

    [path_A moveToPoint:CGPointMake(200, 500)];
    [path_A addLineToPoint:CGPointMake(225, 410)];

    UIBezierPath *path_B = [UIBezierPath bezierPath];

    [path_B moveToPoint:CGPointMake(200, 600)];
    [path_B addLineToPoint:CGPointMake(225, 500)];

    [path_A appendPath:path_B];

    [path_A stroke];

• 创建翻转路径，即起点变成终点，终点变成起点

    UIBezierPath *path = [UIBezierPath bezierPath];

    [path moveToPoint:CGPointMake(50, 50)];
    [path addLineToPoint:CGPointMake(100, 50)];

    path.lineWidth = 5.0f;

    NSLog(@"%@",NSStringFromCGPoint(path.currentPoint));

    UIBezierPath *path_b = [path bezierPathByReversingPath];
    CGAffineTransform transform = CGAffineTransformMakeTranslation(200, 0);
    [path_b applyTransform: transform];
    // 两条路径分别添加一条直接到 self.center
    [path addLineToPoint: CGPointMake(self.frame.size.width*0.5, self.frame.size.height*0.5)];
    [path_b addLineToPoint: CGPointMake(self.frame.size.width*0.5, self.frame.size.height*0.5)];

    NSLog(@"%@",NSStringFromCGPoint(path_b.currentPoint));
    [[UIColor redColor] set];
    [path stroke];
    [[UIColor blueColor] set];
    [path_b stroke];

• 路径进行仿射变换

    UIBezierPath *path = [UIBezierPath bezierPath];

    [path moveToPoint:CGPointMake(100, 50)];
    [path addLineToPoint:CGPointMake(200, 50)];

    CGAffineTransform transform =  CGAffineTransformRotate(self.transform, M_PI_4);
    [path applyTransform:transform];

    path.lineWidth = 5.0f;

    [path stroke];

• 创建虚线

    CGFloat dashStyle[] = {1.0f, 2.0f};

    UIBezierPath *path = [UIBezierPath bezierPath];

    [path moveToPoint:CGPointMake(50, 50)];
    [path addLineToPoint:CGPointMake(100, 50)];

    [path setLineDash:dashStyle count:2 phase:0.0];

    [path stroke];

• 设置颜色

    UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(100, 100, 100, 100)];

    [[UIColor greenColor] setStroke];

    [[UIColor redColor] setFill];

    [path stroke];
    [path fill];

• 设置描边混合模式

    UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(100, 100, 100, 100)];

    [[UIColor greenColor] setStroke];

    path.lineWidth = 10.0f;

    [path strokeWithBlendMode:kCGBlendModeSaturation alpha:1.0];

    [path stroke];

    UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(100, 100, 100, 100)];

    [[UIColor redColor] setFill];

    [path fillWithBlendMode:kCGBlendModeSaturation alpha:0.6];

    [path fill];

• 修改当前图形上下文的绘图区域可见,随后的绘图操作导致呈现内容只有发生在指定路径的填充区域

    UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(100, 100, 100, 100)];

    [[UIColor greenColor] setStroke];

    [path addClip];

    [path stroke];

结语

关于UIBezierPath的简单介绍就到这了,主要是用代码做了展示,属性跟方法,没详细去介绍,我觉得可以直接看苹果的api写的也蛮清楚的.或者自己试试不同的参数样式也能大概理解了.另外简书上看到有篇文章对属性及方法介绍的蛮详细的,可以去看看:UIBezierPath

核心动画跟贝赛尔曲线都有了简单的介绍了,接下来就可以动手做点简单的自定义动画了.