在近期的开发计划中，我们的开发计划有关于商品打分的功能需求列了进来，我就提前看了下，网上的这种demo实在太多了，但是都不是很符合我们的需求，索性自己写一个得了，那就开始动手。先看一下最终效果（最后有demo哦）：
QQ20181115-174009-HD.gif
那有兴趣的同学继续往下看。
先理一下实现思路，我的实现思路是利用CALayer的maskLayer来实现，就跟一般的进度条实现思路差不多,不过这次要用带星的view来做mask。具体实现看下面。
首先写maskLayer的view 也就是带星星的view：
#import <UIKit/UIKit.h>
typedef NS_ENUM(NSInteger, CYXRatingStarStyle) {
RatingStarStyleFull = 0, //满星打分
RatingStarStyleHalf = 1, //可半星打分
};
NS_ASSUME_NONNULL_BEGIN
@interface CYXRatingStarMaskView : UIView
/*星星个数*/
-(instancetype)initWithStarNum:(NSInteger)starNum;
/**
初始化方法
@param starNum 星星个数
@param space 星星直接的间距 默认15
@return self
*/
-(instancetype)initWithStarNum:(NSInteger)starNum andSpace:(CGFloat)space;
/*更新布局 在设置frame之后调用*/
-(void)updateViewConstrains;
/*触摸*/
-(void)touchesWithPoint:(CGPoint)touchPoint;
/*打分风格*/
@property (nonatomic,assign) CYXRatingStarStyle ratingStarStyle;
/*总分*/
@property (nonatomic,assign) NSInteger fullScore;
/*点击 调用block transformPoint转换过的点 score得分*/
@property (nonatomic,strong) void(^touchBlock)(CGPoint transformPoint,NSInteger score);
@end
相关实现（多的我就不再啰嗦了注释里面都有）：
#import "CYXRatingStarMaskView.h"
@interface CYXRatingStarMaskView ()
/*星星个数 最少两个*/
@property (nonatomic,assign) NSInteger starNum;
/*星星间距 默认15*/
@property (nonatomic,assign) CGFloat space;
@property (nonatomic,strong) NSMutableArray *itemList;
@end
@implementation CYXRatingStarMaskView
-(instancetype)initWithStarNum:(NSInteger)starNum{
return [self initWithStarNum:starNum andSpace:15];
}
-(instancetype)initWithStarNum:(NSInteger)starNum andSpace:(CGFloat)space{
if (self = [super init]) {
self.starNum = starNum;
self.space = space;
[self createItems];
}
return self;
}
-(void)createItems{
self.itemList = [NSMutableArray new];
for (int i =0; i<self.starNum; i++) {
UIImageView * item = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"starUnselected"]];
[self.itemList addObject:item];
[self addSubview:item];
}
}
-(void)updateViewConstrains{
if (self.starNum>1) {
CGFloat itemWidth = (self.frame.size.width-(self.starNum -1)*self.space)/self.starNum;
if (itemWidth>0) {
CGFloat x = 0;
for (UIImageView * item in self.itemList) {
item.frame = CGRectMake(x, 0, itemWidth, self.frame.size.height);
x+=itemWidth;
x+=self.space;
}
}
}
}
-(void)touchesWithPoint:(CGPoint)touchPoint{
[self transformPointWithTouchPoint:touchPoint];
}
/*将触点转化成填充星星的点*/
-(CGPoint)transformPointWithTouchPoint:(CGPoint)touchPoint{
/*满星平均分*/
NSInteger average = self.fullScore/[self.itemList count];
/*触摸点x*/
CGFloat x = touchPoint.x;
/*得分*/
CGFloat score = 0;
/*倒序遍历*/
for (NSInteger i = [self.itemList count]-1; i>=0; i--) {
UIImageView * item = self.itemList[i];
if (x>item.frame.origin.x) {
switch (self.ratingStarStyle) {
case RatingStarStyleFull:{//满星
score = (i+1)*average;
x = item.frame.origin.x+item.frame.size.width;
}
break;
case RatingStarStyleHalf:{//支持半星
if (x>(item.frame.origin.x+item.frame.size.width/2)) {//超过半星
score = (i+1)*average;
x = item.frame.origin.x+item.frame.size.width;
}else{
score = (i+1)*average - (average/2);
x = item.frame.origin.x+item.frame.size.width/2;
}
}
break;
default:
break;
}
break;
}
}
CGPoint transformPoint = CGPointMake(x, touchPoint.y);
if (self.touchBlock) {
self.touchBlock(transformPoint, score);
}
return CGPointZero;
}
然后创建用于打分的View来利用这个maskview实现:
#import <UIKit/UIKit.h>
#import "CYXRatingStarMaskView.h"
NS_ASSUME_NONNULL_BEGIN
@interface CYXRatingStarView : UIView
/**
初始化方法
@param frame frame
@param ratingStarStyle 打分风格
@param fullScore 满分
@return self
*/
-(instancetype)initWithFrame:(CGRect)frame
andRatingStarStyle:(CYXRatingStarStyle)ratingStarStyle
andFullScore:(NSInteger)fullScore;
/**
初始化layer 在完成frame赋值后调用一下
*/
-(void)initLayers;
/*选择分数*/
@property (nonatomic,strong) void (^selectScore)(NSInteger score);
@end
相关实现（没啥难点都有注释自己看吧）：
#import "CYXRatingStarView.h"
@interface CYXRatingStarView()
/*背景红色*/
@property (nonatomic,strong) CAShapeLayer *backColorLayer;
@property (nonatomic,strong) CYXRatingStarMaskView *maskView;
@end
@implementation CYXRatingStarView
-(instancetype)initWithFrame:(CGRect)frame
andRatingStarStyle:(CYXRatingStarStyle)ratingStarStyle
andFullScore:(NSInteger)fullScore{
if (self = [super initWithFrame:frame]) {
self.backgroundColor = [UIColor whiteColor];
self.maskView.fullScore = fullScore;
self.maskView.ratingStarStyle = ratingStarStyle;
[self.layer addSublayer:self.backColorLayer];
}
return self;
}
-(void)initLayers{
self.maskView.frame = self.bounds;
[self.maskView updateViewConstrains];
self.backColorLayer.frame = self.bounds;
UIBezierPath *path = [UIBezierPath bezierPath];
[path moveToPoint:CGPointMake(0, self.frame.size.height/2)];
[path addLineToPoint:CGPointMake(self.frame.size.width, self.frame.size.height/2)];
self.backColorLayer.path = path.CGPath;
self.backColorLayer.lineWidth = self.frame.size.height;
self.backColorLayer.mask = self.maskView.layer;
self.backColorLayer.strokeEnd = 0;
}
/*设置选择的星星*/
-(void)setStrokeWithTransformPoint:(CGPoint)transformPoint{
CGPoint newPoint = [self convertPoint:transformPoint fromView:self.maskView];
NSLog(@"%f",newPoint.x);
self.backColorLayer.strokeEnd = newPoint.x/self.frame.size.width;
}
/*一根或者多根手指开始触摸view，系统会自动调用view的下面方法*/
-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
//获取touch
UITouch * touch = [touches anyObject];
//获取当前点
CGPoint touchPoint = [touch locationInView:self];
CGPoint newPoint = [self convertPoint:touchPoint toView:self.maskView];
[self.maskView touchesWithPoint:newPoint];
}
#pragma mark ---G
-(CAShapeLayer*)backColorLayer{
if(!_backColorLayer){
_backColorLayer = [[CAShapeLayer alloc] init];
_backColorLayer.backgroundColor = [UIColor grayColor].CGColor;//在这里是未填充的颜色
_backColorLayer.fillColor = [UIColor clearColor].CGColor; // 填充色为透明（不设置为黑色）
//_backColorLayer.lineCap = kCALineCapSquare; // 设置线为圆角
_backColorLayer.strokeColor = [UIColor redColor].CGColor; // 路径颜色颜色（填充颜色）
}
return _backColorLayer;
}
-(CYXRatingStarMaskView*)maskView{
if(!_maskView){
__weak __typeof(&*self)weakSelf = self;
_maskView = [[CYXRatingStarMaskView alloc] initWithStarNum:5];
_maskView.touchBlock = ^(CGPoint transformPoint, NSInteger score) {
NSLog(@"%@",NSStringFromCGPoint(transformPoint));
NSLog(@"%ld",(long)score);
[weakSelf setStrokeWithTransformPoint:transformPoint];
if (weakSelf.selectScore) {
weakSelf.selectScore(score);
}
};
}
return _maskView;
}
总体写下来思路还是很明确的，而且实现过程当中并没有什么疑难杂症，有什么问题欢迎讨论。
demo地址：https://github.com/SionChen/CYXRatingStarViewDemo
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