一、使用CAShapeLayer實現複雜的View的遮罩效果

1.1、案例演示

最近在整理一個聊天的專案的時候，傳送圖片的時候，會有一個三角的指向效果，指向這張圖片的傳送者。服務端返回給我們的圖片只是一張矩形的圖片，我們如何把一張矩形的圖片或者View，加上一層自定義遮罩效果，就是本文要講的內容。效果演示如下：第一張是一個View的遮罩效果，第二張是UIImageView的遮罩效果。

演示圖片

1.2、實現機制

在每一View的layer層中有一個mask屬性，他就是專門來設定該View的遮罩效果的。該mask本身也是一個layer層。我們只需要生成一個自定義的layer，然後覆蓋在需要遮罩的View上面即可。問題就歸於如何生成入上圖所示的不規則圖片的Layer。CAShapeLayer可以根據幾個點的依次連線，產生一個閉合空間的layer。如下圖所示：

這裡寫圖片描述

1.3、實現程式碼

實現方式為實現了CAShapeLayer的ViewMask的Category。

Objective-C @implementation CAShapeLayer (ViewMask) + (instancetype)createMaskLayerWithView : (UIView *)view{ CGFloat viewWidth = CGRectGetWidth(view.frame); CGFloat viewHeight = CGRectGetHeight(view.frame); CGFloat rightSpace = 10.; CGFloat topSpace = 15.; CGPoint point1 = CGPointMake(0, 0); CGPoint point2 = CGPointMake(viewWidth-rightSpace, 0); CGPoint point3 = CGPointMake(viewWidth-rightSpace, topSpace); CGPoint point4 = CGPointMake(viewWidth, topSpace); CGPoint point5 = CGPointMake(viewWidth-rightSpace, topSpace+10.); CGPoint point6 = CGPointMake(viewWidth-rightSpace, viewHeight); CGPoint point7 = CGPointMake(0, viewHeight); UIBezierPath *path = [UIBezierPath bezierPath]; [path moveToPoint:point1]; [path addLineToPoint:point2]; [path addLineToPoint:point3]; [path addLineToPoint:point4]; [path addLineToPoint:point5]; [path addLineToPoint:point6]; [path addLineToPoint:point7]; [path closePath]; CAShapeLayer *layer = [CAShapeLayer layer]; layer.path = path.CGPath; return layer; } @end

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@implementationCAShapeLayer(ViewMask)+(instancetype)createMaskLayerWithView :(UIView*)view{CGFloatviewWidth=CGRectGetWidth(view.frame);CGFloatviewHeight=CGRectGetHeight(view.frame);CGFloatrightSpace =10.;CGFloattopSpace=15.;CGPointpoint1=CGPointMake(0,0);CGPointpoint2=CGPointMake(viewWidth-rightSpace,0);CGPointpoint3=CGPointMake(viewWidth-rightSpace,topSpace);CGPointpoint4=CGPointMake(viewWidth,topSpace);CGPointpoint5=CGPointMake(viewWidth-rightSpace,topSpace+10.);CGPointpoint6=CGPointMake(viewWidth-rightSpace,viewHeight);CGPointpoint7=CGPointMake(0,viewHeight);UIBezierPath*path=[UIBezierPathbezierPath];[path moveToPoint:point1];[path addLineToPoint:point2];[path addLineToPoint:point3];[path addLineToPoint:point4];[path addLineToPoint:point5];[path addLineToPoint:point6];[path addLineToPoint:point7];[path closePath];CAShapeLayer*layer=[CAShapeLayerlayer];layer.path=path.CGPath;returnlayer;}@end

1.4、呼叫方式

Objective-C UIView *view = [[UIView alloc] initWithFrame:CGRectMake(40, 50, 80, 100)]; view.backgroundColor = [UIColor orangeColor]; [self.view addSubview:view]; CAShapeLayer *layer = [CAShapeLayer createMaskLayerWithView:view]; view.layer.mask = layer;

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UIView*view=[[UIViewalloc] initWithFrame:CGRectMake(40,50,80,100)];view.backgroundColor=[UIColororangeColor];[self.view addSubview:view];CAShapeLayer*layer=[CAShapeLayer createMaskLayerWithView:view];view.layer.mask=layer;

二、使用CAShapeLayer實現一個音量大小動態改變的控制元件

2.1、案例演示

對於實時顯示語音音量大小的需求，發現很多人的實現方式通過預放置多張圖進行切換進行完成的。這樣的處理，不但會浪費App的資源儲存空間，而且效率也不高。對於符合某一定規律動態改變的圖形，我們也可以考慮通過程式碼的方式來實現。

演示圖片

2.2、實現機制

描述

外部輪廓View主要控制顯示大小和顯示的圓角效果。內部的Layer主要控制動態顯示的高度，雖然他是矩形的。但是當把該Layer加入到View中，而該View設定了_dynamicView.clipsToBounds = YES;。內部的Layer超過外部輪廓的部分，則會被切除掉。

如此說來，我們只需要動態改變內部Layer顯示的高度，即可完成該效果顯示。是不是很簡單啊。。

2.3、實現程式碼

_dynamicView 表示外部輪廓的View。

indicateLayer 表示內容動態顯示的Layer。

實現動態改變的函式如下：

Objective-C -(void)refreshUIWithVoicePower : (NSInteger)voicePower{ CGFloat height = (voicePower)*(CGRectGetHeight(_dynamicView.frame)/TOTAL_NUM); [_indicateLayer removeFromSuperlayer]; _indicateLayer = nil; UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(0, CGRectGetHeight(_dynamicView.frame)-height, CGRectGetWidth(_dynamicView.frame), height) cornerRadius:0]; _indicateLayer = [CAShapeLayer layer]; _indicateLayer.path = path.CGPath; _indicateLayer.fillColor = [UIColor whiteColor].CGColor; [_dynamicView.layer addSublayer:_indicateLayer]; }

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-(void)refreshUIWithVoicePower :(NSInteger)voicePower{CGFloatheight=(voicePower)*(CGRectGetHeight(_dynamicView.frame)/TOTAL_NUM);[_indicateLayer removeFromSuperlayer];_indicateLayer=nil;UIBezierPath*path=[UIBezierPath bezierPathWithRoundedRect:CGRectMake(0,CGRectGetHeight(_dynamicView.frame)-height,CGRectGetWidth(_dynamicView.frame),height) cornerRadius:0];_indicateLayer=[CAShapeLayerlayer];_indicateLayer.path=path.CGPath;_indicateLayer.fillColor=[UIColorwhiteColor].CGColor;[_dynamicView.layer addSublayer:_indicateLayer];}

三、圓形進度條

3.1、案例演示

最近有一個小需求，就是要做一個圓形進度條，大概樣子如下：

演示圖片

。
在不知道有CAShapeLayer的strokeStart和strokeEnd屬性的時候，我採取的方法就是實時的 移除舊的CAShapeLayer 然後重繪這個圓形的CAShapeLayer。顯然這種方式的效率是不高的。後來在一次看別人Demo的時候，發現別人使用了CAShapeLayer的strokeStart和strokeEnd屬性，實現這一個效果十分的簡單方便。下面就和大家來講一講這兩個屬性的使用。

3.2、屬性詳解

蘋果官方給出這兩個屬性的解釋為：
/* These values define the subregion of the path used to draw the

• stroked outline. The values must be in the range [0,1] with zero
• representing the start of the path and one the end. Values in
• between zero and one are interpolated linearly along the path
• length. strokeStart defaults to zero and strokeEnd to one. Both are
• animatable. */
  大概意思就是：我們可以對繪製的Path進行分割槽。這兩個屬性的值在0~1之間，0代表Path的開始位置，1代表Path的結束位置。是一種線性遞增關係。strokeStart預設值為0，strokeEnd預設值為1。這兩個屬性都支援動畫。

Objective-C CAShapeLayer *shapeLayer = [CAShapeLayer layer]; shapeLayer.frame = _demoView.bounds; shapeLayer.strokeEnd = 0.7f; shapeLayer.strokeStart = 0.1f; UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:_demoView.bounds]; shapeLayer.path = path.CGPath; shapeLayer.fillColor = [UIColor clearColor].CGColor; shapeLayer.lineWidth = 2.0f; shapeLayer.strokeColor = [UIColor redColor].CGColor; [_demoView.layer addSublayer:shapeLayer];

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CAShapeLayer*shapeLayer=[CAShapeLayerlayer];shapeLayer.frame=_demoView.bounds;shapeLayer.strokeEnd=0.7f;shapeLayer.strokeStart=0.1f;UIBezierPath*path=[UIBezierPath bezierPathWithOvalInRect:_demoView.bounds];shapeLayer.path=path.CGPath;shapeLayer.fillColor=[UIColorclearColor].CGColor;shapeLayer.lineWidth=2.0f;shapeLayer.strokeColor=[UIColorredColor].CGColor;[_demoView.layer addSublayer:shapeLayer];

我們通過以上程式碼設定：strokeStart=0.1f; strokeEnd=0.7f則顯示如下圖所示。

演示圖片

3.3、圓形進度條的實現程式碼

Objective-C CAShapeLayer *shapeLayer = [CAShapeLayer layer]; shapeLayer.frame = _demoView.bounds; UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:_demoView.bounds]; shapeLayer.path = path.CGPath; shapeLayer.fillColor = [UIColor clearColor].CGColor; shapeLayer.lineWidth = 2.0f; shapeLayer.strokeColor = [UIColor redColor].CGColor; [_demoView.layer addSublayer:shapeLayer]; CABasicAnimation *pathAnima = [CABasicAnimation animationWithKeyPath:@"strokeEnd"]; pathAnima.duration = 3.0f; pathAnima.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]; pathAnima.fromValue = [NSNumber numberWithFloat:0.0f]; pathAnima.toValue = [NSNumber numberWithFloat:1.0f]; pathAnima.fillMode = kCAFillModeForwards; pathAnima.removedOnCompletion = NO; [shapeLayer addAnimation:pathAnima forKey:@"strokeEndAnimation"];

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CAShapeLayer*shapeLayer=[CAShapeLayerlayer];shapeLayer.frame=_demoView.bounds;UIBezierPath*path=[UIBezierPath bezierPathWithOvalInRect:_demoView.bounds];shapeLayer.path=path.CGPath;shapeLayer.fillColor=[UIColorclearColor].CGColor;shapeLayer.lineWidth=2.0f;shapeLayer.strokeColor=[UIColorredColor].CGColor;[_demoView.layer addSublayer:shapeLayer];CABasicAnimation*pathAnima=[CABasicAnimation animationWithKeyPath:@"strokeEnd"];pathAnima.duration=3.0f;pathAnima.timingFunction=[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];pathAnima.fromValue=[NSNumber numberWithFloat:0.0f];pathAnima.toValue=[NSNumber numberWithFloat:1.0f];pathAnima.fillMode=kCAFillModeForwards;pathAnima.removedOnCompletion=NO;[shapeLayer addAnimation:pathAnima forKey:@"strokeEndAnimation"];

四、聯絡方式

歡迎加好友、一起交流。