小知识，大挑战！本文正在参与“程序员必备小知识”创作活动。
引言
原理：利用CoreGraphics进行自定义转盘的绘制
下载完整Demo:download.csdn.net/download/u0…
在app侧控制中奖奖品，有两种方式
方式一： 发起网络请求获取当前选中奖品(推荐)，即由服务侧控制中奖数据，更安全
方式二：根据奖品百分比进行控制中奖概率
I、根据奖品百分比进行控制中奖概率
- 根据中奖概率probability 确定随机中奖范围probabilityRange
- 根据随机中奖范围probabilityRange，确定中奖奖品
1.1 定义奖品模型
#import <Foundation/Foundation.h>
NS_ASSUME_NONNULL_BEGIN
@interface KNTurntableViewModel : NSObject
@property (nonatomic, assign) NSInteger index;
@property (nonatomic, copy) NSString *title;
@property (nonatomic, copy) NSString *imageName;
@property (nonatomic, copy) NSString *icon;
/**
该奖品的中奖概率
*/
@property (nonatomic, assign) double probability;
//
@property (nonatomic, assign) NSRange probabilityRange;
/**
根据奖品的中奖概率获取中奖奖品
*/
+(instancetype)getMbyprobabilityRangeWithArr:(NSArray*)arr;
@end
NS_ASSUME_NONNULL_END
复制代码1.2 根据奖品的中奖概率获取中奖奖品
- 根据随机中奖范围probabilityRange，确定中奖奖品
// 根据奖品百分比进行控制：
// 奖品 title A ，index下标0，中奖 概率probability80%， 就是当randomNum为0-80，返回中奖下标0
// 为了便于理解，我们称奖品A的【随机中奖范围】 probabilityRange为0-80
//
// 根据randomNum，确定中奖奖品
+ (instancetype)getMbyprobabilityRangeWithArr:(NSArray *)arr {
NSInteger randomNum = arc4random()%100;//控制概率
NSLog(@"randomNum:%@",[NSNumber numberWithDouble:randomNum]);
for (KNTurntableViewModel *obj in arr) {
NSLog(@"obj probabilityRange loc:%@ len %@", [NSNumber numberWithDouble:obj.probabilityRange.location],[NSNumber numberWithDouble:obj.probabilityRange.location+obj.probabilityRange.length]
);
if (randomNum>=obj.probabilityRange.location && randomNum<obj.probabilityRange.location+obj.probabilityRange.length) {//80%的概率 就是0-80
return obj;
}
}
return nil;// 谢谢参与
}
复制代码1.3 构造数据模型
- 根据中奖概率probability 确定随机中奖范围probabilityRange
- (KNTurntableViewM *)viewModel{
if(_viewModel == nil){
_viewModel = [KNTurntableViewM new];
NSMutableArray * luckyItemArray = [NSMutableArray array];
double probabilityRangeLoc = 0;
double probabilityRangeLen = 0;
for (int i = 0; i < 6; i++) {//
KNTurntableViewModel *model = [[KNTurntableViewModel alloc] init];
model.title = [NSString stringWithFormat:@"%d-标题",i];
model.index = i;
if(i == 1){
model.probability = 0.5;
}else{
model.probability =0.1;
}
// 初始化probabilityRange
probabilityRangeLoc = probabilityRangeLoc +probabilityRangeLen;
probabilityRangeLen = i+100*model.probability;
//probabilityRange 的计算不要包括谢谢参与的概率
model.probabilityRange = NSMakeRange(probabilityRangeLoc, probabilityRangeLen);
model.imageName = @"qrcode_for_gh";
model.icon = @"https://img-blog.csdnimg.cn/20201114103143654.JPG?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEwMTg5Nzk=,size_16,color_FFFFFF,t_70#pic_center";
[luckyItemArray addObject:model];
}
_viewModel.luckyItemArray = luckyItemArray;
}
return _viewModel ;
}
复制代码II、转盘算法
2.1 旋转到指定下标奖品
- 旋转到指定下标奖品
/**
转盘算法
*/
- (void)animationWithSelectonIndex:(NSInteger)index{
[self backToStartPosition];
double perSection = M_PI*2/_luckyItemArray.count;
// //先转4圈 再选区 顺时针(所有这里需要用360-对应的角度) 逆时针不需要
double toValue= ((M_PI*2 - (perSection*index +perSection*0.5)) + M_PI*2*4);
[self RotationWithEndValue: @(toValue - M_PI/2) duration:4 delegate:self];// 因为drawRect从正3点开始画，因此- M_PI/2
}
- (void)RotationWithEndValue:(id)toValue duration:(CFTimeInterval)duration delegate:(id)delegate{
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"transform.rotation"];
animation.toValue = toValue;//
animation.duration = duration;
//由快变慢
animation.removedOnCompletion = NO;
animation.fillMode = kCAFillModeForwards;
animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseOut];//
animation.delegate = delegate;
[self.layer addAnimation:animation forKey:@"rotation"];
}
复制代码- 恢复起始位置
-(void)backToStartPosition{
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"transform.rotation"];
animation.toValue = @(0);
animation.duration = 0.001;
animation.removedOnCompletion = NO;
animation.fillMode = kCAFillModeForwards;
[self.layer addAnimation:animation forKey:@"rotation"];
}
复制代码2.2 处理旋转结束事件
- CAAnimationDelegate，处理旋转结束事件
#pragma mark - CAAnimationDelegate
- (void)animationDidStart:(CAAnimation *)anim{
}
- (void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag{
if (self.rotaryEndTurnBlock) {
self.rotaryEndTurnBlock();
}
}
复制代码III、iOS 抽奖轮盘边框动画
blog.csdn.net/z929118967/… 原理： 用NSTimer无限替换UIImageView的Image为互为错位的bg_horse_race_lamp_1或者bg_horse_race_lamp_2，达到跑马灯的效果
- 应用场景： iOS 抽奖轮盘边框动画
审核注意事项： 1、在抽奖页面添加一句文案“本活动与苹果公司无关”
2、在提交审核时修改分级至17+
3.1 实现代码
//
// ViewController.m
// horse_race_lamp
//
// Created by mac on 2021/4/7.
#import <Masonry/Masonry.h>
#import "ViewController.h"
NSString *const bg_horse_race_lamp_1=@"bg_horse_race_lamp_1";
NSString *const bg_horse_race_lamp_2=@"bg_horse_race_lamp_2";
@interface ViewController ()
/**
用NSTimer无限替换bg_horse_race_lamp_1和bg_horse_race_lamp_2，达到跑马灯的效果
应用场景： iOS 抽奖轮盘边框动画
*/
@property (nonatomic,strong) UIImageView *rotaryTable;
@property (nonatomic,strong) NSTimer *itemBordeTImer;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.
//通过以下两张图片bg_lamp_1 bg_lamp_2，用NSTimer无限替换，达到跑马灯的效果
_rotaryTable = [UIImageView new];
_rotaryTable.tag = 100;
[_rotaryTable setImage:[UIImage imageNamed:bg_horse_race_lamp_1]];
[self.view addSubview:_rotaryTable];
[_rotaryTable mas_makeConstraints:^(MASConstraintMaker *make) {
make.center.offset(0);
}];
_itemBordeTImer = [NSTimer scheduledTimerWithTimeInterval:0.5 target:self selector:@selector(itemBordeTImerEvent) userInfo:nil repeats:YES];
[[NSRunLoop currentRunLoop] addTimer:_itemBordeTImer forMode:NSRunLoopCommonModes];
}
// 边框动画
- (void)itemBordeTImerEvent
{
if (_rotaryTable.tag == 100) {
_rotaryTable.tag = 101;
[_rotaryTable setImage:[UIImage imageNamed:bg_horse_race_lamp_2]];
}else if (_rotaryTable.tag == 101){
_rotaryTable.tag = 100;
[_rotaryTable setImage:[UIImage imageNamed:bg_horse_race_lamp_1]];
}
}
@end
复制代码3.2 从CSDN下载Demo
从CSDN下载Demo：https://download.csdn.net/download/u011018979/16543761
see also
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