UIBezierPath主要用來繪制矢量圖形，它是基于Core Graphics對CGPathRef數據類型和path繪圖屬性的一個封裝，所以是需要圖形上下文的（CGContextRef），所以一般UIBezierPath在drawRect中使用。
使用方法
UIBezierPath 是對 CGPathRef 的封裝。創建矢量圖形時，拆解成一或多條線段，拼接起來，每條線段的終點都是下一條線段的起點。
具體地：
1.創建一個 UIBezierPath 對象
2.用 moveToPoint: 設置初始線段的起點
3.添加線段，定義一或多個子路徑
4.修改 UIBezierPath 的繪圖相關的屬性，比如stroke path的屬性 lineWidth 和 lineJoinStyle ，filled path的屬性 usesEvenOddFillRule
注意:如果是矩形或者圓之類的特殊圖形，可以不用第2步。
代碼案例
畫直線
UIBezierPath *path = [UIBezierPath bezierPath]; [path moveToPoint:CGPointMake(50, 50)]; [path addLineToPoint:CGPointMake(100, 50)]; path.lineWidth = 5.0f; path.lineJoinStyle = kCGLineJoinRound; [path stroke];
創建三角形
UIBezierPath *path = [UIBezierPath bezierPath]; [path moveToPoint:CGPointMake(50, 50)]; [path addLineToPoint:CGPointMake(300, 50)]; [path addLineToPoint:CGPointMake(200, 150)]; // 最后的閉合線是可以通過調用closePath方法來自動生成的，也可以調用-addLineToPoint:方法來添加 // [path addLineToPoint:CGPointMake(50, 50)]; [path closePath]; path.lineWidth = 5.0f; [path stroke];
創建矩形
UIBezierPath *path = [UIBezierPath bezierPathWithRect:CGRectMake(50, 100, 50, 50)]; path.lineWidth = 5.0f; [path stroke];
創建內切曲線
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];
創建帶有圓角的矩形，當矩形變成正圓的時候，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];
設定特定的角為圓角的矩形
UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(50, 400, 50, 50) byRoundingCorners:UIRectCornerBottomLeft cornerRadii:CGSizeMake(5,5)]; path.lineWidth = 5.0f; [path stroke];
創建圓弧
UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:CGPointMake(100, 550) radius:25 startAngle:0 endAngle:1.5*M_PI clockwise:YES]; path.lineWidth = 5.0f; [path stroke];
通過路徑A創建路徑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];
創建三次貝塞爾曲線
UIBezierPath *path = [UIBezierPath bezierPath]; [path moveToPoint:CGPointMake(100, 200)]; [path addCurveToPoint:CGPointMake(300, 200) controlPoint1:CGPointMake(150, 150) controlPoint2:CGPointMake(250, 250)]; [path stroke];
創建二次貝塞爾曲線
UIBezierPath *path = [UIBezierPath bezierPath]; [path moveToPoint:CGPointMake(100, 200)]; [path addQuadCurveToPoint:CGPointMake(300, 200) controlPoint:CGPointMake(150, 150)]; [path stroke];
添加圓弧
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];
追加路徑
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];
創建翻轉路徑，即起點變成終點，終點變成起點
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]; // 兩條路徑分別添加一條直接到 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];
路徑進行仿射變換
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];
創建虛線
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];
設置顏色
UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(100, 100, 100, 100)]; [[UIColor greenColor] setStroke]; [[UIColor redColor] setFill]; [path stroke]; [path fill];
設置描邊混合模式
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];
修改當前圖形上下文的繪圖區域可見,隨后的繪圖操作導致呈現內容只有發生在指定路徑的填充區域
UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(100, 100, 100, 100)]; [[UIColor greenColor] setStroke]; [path addClip]; [path stroke];
結語
關于UIBezierPath的簡單介紹就到這了,主要是用代碼做了展示,屬性跟方法,沒詳細去介紹,我覺得可以直接看蘋果的api寫的也蠻清楚的.或者自己試試不同的參數樣式也能大概理解了.
核心動畫跟貝賽爾曲線都有了簡單的介紹了,接下來就可以動手做點簡單的自定義動畫了.
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