评分功能

iOS系统中没有自带的星星评分功能，需要自己封装。星星评分功能是整个工程的一个需求，但是代码的封装则是一个代码功底和编程思维的考验。

星星评分封装代码部分：

#import 
@interface StarsView : UIView
// 分值，范围1~5，默认5
@property (nonatomic, assign) CGFloat score;
// block 传值
@property (nonatomic, copy) void (^selectedStars)(CGFloat starScore);
@end

设定变动参数，这里最好是定义成全局的，修改起来比较方便

#import "StarsView.h"
#define SELECT_STAR @"icon_star_green"
#define UNSELECT_STAR @"icon_star_gray"
#define DEFALUT_STAR_NUMBER 5
#define ANIMATION_TIME_INTERVAL 0.1

#define  SCREEN_WIDTH [UIScreen mainScreen].bounds.size.width
#define  SCREEN_HEIGHT [UIScreen mainScreen].bounds.size.height

@interface StarsView ()
// 选中图层
@property (nonatomic, strong) UIView * selectView;
// 未选中图层
@property (nonatomic, strong) UIView * unSelectView;
// 星星的数量
@property (nonatomic, assign) NSInteger numberOfStar;
@end
@implementation StarsView
- (instancetype)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        self.backgroundColor = [UIColor whiteColor];
        // 设置星星布局
        [self configStarScoreView];
    }
    return self;
}

- (void)layoutSubviews {
    [super layoutSubviews];
    __weak typeof(self) weakself = self;
    [UIView animateWithDuration:ANIMATION_TIME_INTERVAL animations:^{
       
        weakself.selectView.frame = CGRectMake(0, 0, weakself.bounds.size.width /  weakself.numberOfStar * weakself.score, weakself.bounds.size.height);
    }];
}

// 设置星星布局
- (void)configStarScoreView {
    
    _numberOfStar = DEFALUT_STAR_NUMBER; // 默认星星为5颗
    // 选中图层
    _selectView = [self createStarViewWithImage:SELECT_STAR];
    // 未选中图层
    _unSelectView = [self createStarViewWithImage:UNSELECT_STAR];
    [self addSubview:self.unSelectView];
    [self addSubview:self.selectView];
    // 添加手势
    UITapGestureRecognizer * tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(starTapGesture:)];
    tapGesture.numberOfTapsRequired = 1;
    [self addGestureRecognizer:tapGesture];
}

// 星星触摸手势
- (void)starTapGesture:(UITapGestureRecognizer *)gesture {
    // 定位手势的位置
    CGPoint tapPoint = [gesture locationInView:self];
    CGFloat offset = tapPoint.x;
    // 星星的位置
    CGFloat positionStar = offset / (self.bounds.size.width / self.numberOfStar);
    // 分数取整
    self.score = ceilf(positionStar);
}

#pragma mark -  创建星星图层
- (UIView *)createStarViewWithImage:(NSString *)imageName {
    
    UIView *view = [[UIView alloc] initWithFrame:self.bounds];
    view.clipsToBounds = YES;
    view.backgroundColor = [UIColor clearColor];
    for (NSInteger i = 0; i < self.numberOfStar; i ++) {
        
        UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:imageName]];
        CGFloat with = self.bounds.size.width / self.numberOfStar;
        imageView.frame = CGRectMake(i * with, 0, with, self.bounds.size.height);
        imageView.contentMode = UIViewContentModeScaleAspectFit;
        [view addSubview:imageView];
    }
    return view;
}

#pragma mark - GET and SET 
- (void)setScore:(CGFloat)score {
    if (_score != score) {
        _score = score;
    }
    if (self.selectedStars) {
        self.selectedStars(score);
    }
    [self setNeedsLayout];
}
@end