我正在尝试为 UIBezierPath 制作动画，并且我已经安装了 CAShapeLayer 来尝试执行此操作。不幸的是，动画不工作，我不确定任何层是否有任何影响(因为代码正在做与我拥有层之前所做的相同的事情)。

这是实际代码 - 希望得到任何帮助。 Draw2D 是嵌入在 UIViewController 中的 UIView 的实现。所有绘图都发生在 Draw2D 类中。调用 [_helper createDrawing...] 只是用点填充 _uipath 变量。

Draw2D.h 定义了以下属性:

#define defaultPointCount ((int) 25)

@property Draw2DHelper *helper;
@property drawingTypes drawingType;
@property int graphPoints;
@property UIBezierPath *uipath;

@property CALayer *animationLayer;
@property CAShapeLayer *pathLayer;

- (void)refreshRect:(CGRect)rect;

下面是实际的实现:

//
//  Draw2D.m
//  Draw2D
//
//  Created by Marina on 2/19/13.
//  Copyright (c) 2013 Marina. All rights reserved.
//

#import "Draw2D.h"
#import"Draw2DHelper.h"
#include <stdlib.h>
#import "Foundation/Foundation.h"
#import <QuartzCore/QuartzCore.h>

int MAX_WIDTH;
int MAX_HEIGHT;

@implementation Draw2D

- (id)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code

        if (self.pathLayer != nil) {
            [self.pathLayer removeFromSuperlayer];
            self.pathLayer = nil;
        }

        self.animationLayer = [CALayer layer];
        self.animationLayer.frame = self.bounds;
        [self.layer addSublayer:self.animationLayer];

        CAShapeLayer *l_pathLayer = [CAShapeLayer layer];
        l_pathLayer.frame = self.frame;
        l_pathLayer.bounds = self.bounds;
        l_pathLayer.geometryFlipped = YES;
        l_pathLayer.path = _uipath.CGPath;
        l_pathLayer.strokeColor = [[UIColor grayColor] CGColor];
        l_pathLayer.fillColor = nil;
        l_pathLayer.lineWidth = 1.5f;
        l_pathLayer.lineJoin = kCALineJoinBevel;

        [self.animationLayer addSublayer:l_pathLayer];
        self.pathLayer = l_pathLayer;
        [self.layer addSublayer:l_pathLayer];
    }
    return self;
}

// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect :(int) points :(drawingTypes) type //:(Boolean) initial
{
    //CGRect bounds = [[UIScreen mainScreen] bounds];
    CGRect appframe= [[UIScreen mainScreen] applicationFrame];
    CGContextRef context = UIGraphicsGetCurrentContext();
    _helper = [[Draw2DHelper alloc ] initWithBounds :appframe.size.width  :appframe.size.height :type];

    CGPoint startPoint = [_helper generatePoint] ;

    [_uipath moveToPoint:startPoint];
    [_uipath setLineWidth: 1.5];

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

    CGPoint center = CGPointMake(self.center.y, self.center.x) ;
    [_helper createDrawing :type :_uipath :( (points>0) ? points : defaultPointCount) :center];
    self.pathLayer.path = (__bridge CGPathRef)(_uipath);
    [_uipath stroke];

    [self startAnimation]; 
}

- (void) startAnimation {
    [self.pathLayer removeAllAnimations];

    CABasicAnimation *pathAnimation = [CABasicAnimation animationWithKeyPath:@"strokeEnd"];
    pathAnimation.duration = 3.0;
    pathAnimation.fromValue = [NSNumber numberWithFloat:0.0f];
    pathAnimation.toValue = [NSNumber numberWithFloat:1.0f];
    [self.pathLayer addAnimation:pathAnimation forKey:@"strokeEnd"];

}

- (void)drawRect:(CGRect)rect {
    if (_uipath == NULL)
        _uipath = [[UIBezierPath alloc] init];
    else
        [_uipath removeAllPoints];

    [self drawRect:rect  :self.graphPoints :self.drawingType ];
}

- (void)refreshRect:(CGRect)rect {
    [self setNeedsDisplay];
}

@end

我知道可能有一个明显的原因导致路径在绘制时没有动画(而不是立即显示，这是现在发生的情况)但我已经盯着这个东西看了很长时间以至于我只是看不到它。

此外，如果有人可以推荐有关 CAShapeLayers 和一般动画的基本入门，我将不胜感激。还没有遇到任何足够好的。

提前致谢。

最佳答案

看起来您正在尝试在 drawRect 中制作动画(至少是间接的)。这不太合理。您不在 drawRect 中设置动画。 drawRect 用于绘制单帧。一些动画是用定时器或 CADisplayLink 重复调用 setNeedsDisplay(这将导致 iOS 调用你的 drawRect)完成的，在此期间你可能会绘制单个显示当时动画进度的帧。但是您根本没有 drawRect 自行启动任何动画。

但是，由于您使用的是 Core Animation 的 CAShapeLayer 和 CABasicAnimation，因此您根本不需要自定义 drawRect。 Quartz 的 Core Animation 会为你处理好一切。例如，这是我为 UIBezierPath 绘制动画的代码:

#import <QuartzCore/QuartzCore.h>

@interface View ()
@property (nonatomic, weak) CAShapeLayer *pathLayer;
@end

@implementation View

/*
// I'm not doing anything here, so I can comment this out
- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code
    }
    return self;
}
*/

/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
    // Drawing code
}
*/

// It doesn't matter what my path is. I could make it anything I wanted.

- (UIBezierPath *)samplePath
{
    UIBezierPath *path = [UIBezierPath bezierPath];

    // build the path here

    return path;
}

- (void)startAnimation
{
    if (self.pathLayer == nil)
    {
        CAShapeLayer *shapeLayer = [CAShapeLayer layer];

        shapeLayer.path = [[self samplePath] CGPath];
        shapeLayer.strokeColor = [[UIColor grayColor] CGColor];
        shapeLayer.fillColor = nil;
        shapeLayer.lineWidth = 1.5f;
        shapeLayer.lineJoin = kCALineJoinBevel;

        [self.layer addSublayer:shapeLayer];

        self.pathLayer = shapeLayer;
    }

    CABasicAnimation *pathAnimation = [CABasicAnimation animationWithKeyPath:@"strokeEnd"];
    pathAnimation.duration = 3.0;
    pathAnimation.fromValue = @(0.0f);
    pathAnimation.toValue = @(1.0f);
    [self.pathLayer addAnimation:pathAnimation forKey:@"strokeEnd"];
}

@end

然后，当我想开始绘制动画时，只需调用我的 startAnimation 方法即可。对于像这样简单的事情，我什至可能根本不需要 UIView 子类，因为我实际上并没有改变任何 UIView 行为。肯定有很多次您使用自定义 drawRect 实现子类化 UIView，但这里不需要。

您要求提供一些引用资料:

• 我可能会先回顾一下 Apple 的 Core Animation Programming Guide ，如果你还没有看到的话。
• 对我来说，当我通过 Mike Nachbaur's Core Animation Tutorial Part 4 时，一切都明白了，实际上是从头开始复制他的演示。显然，您也可以查看第 1 部分到第 3 部分。

关于ios - 如何使用 CAShapeLayer 使我的 UIBezierPath 动画化？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/15318918/