#import <UIKit/UIKit.h>

typedef NS_ENUM(NSInteger, MoveStatus) {
    Start,
    Enter,
    End
};

@interface BulletView: UIView

@property (nonatomic, assign) int trajectory; //弹道
@property (nonatomic, copy) void(^moveStatusBlock)(MoveStatus status); // 弹幕状态回调

//初始化弹幕
- (instancetype)initWithComment:(NSString*)comment;

//开始动画
- (void)startAnimation;

//结束动画
- (void)stopAnimation;
@end

#import "BulletView.h"

#define Padding 10;
#define PhotoHeight 30;

@interface BulletView ()

@property (nonatomic, strong) UILabel *lbComment;
 
@property (nonatomic, strong) UIImageView *photoIgv;

@end

@implementation BulletView

//初始化弹幕
- (instancetype)initWithComment:(NSString *)comment {
    if (self = [super init]) {
        self.backgroundColor = [UIColor redColor];
        self.layer.cornerRadius = 15;
        NSDictionary *attr = @{NSFontAttributeName:[UIFont systemFontOfSize:14]};
        CGFloat width = [comment sizeWithAttribute:attr].width;
        self.bounds = CGRectMake(0, 0, width + 2 * Padding + PhotoHeight, 30);
        self.lbComment.text = comment;
        self.lbcomment.frame = CGRectMake(Padding + PhotoHeight, 0, width, 30);

        self.bphotoIgv.frame = CGRectMake(-Padding, -Padding, PhotoHeight + Padding, PhotoHeight + Padding);
        self.layer.cornerRadius = () / 2;
        self.photoIgv.layer.borderColor = [UIColor orangeColor].CGColor;
        self.photoIgv.layer.borderWidath = 1;
        self.photoIgv.img = [UIImage imageNamed:@""];
    }
    return self;
}

//开始动画
- (void)startAnimation {
    CGFloat screenWidth = [UIScreen mainScreen].bounds.size.width;
    CGFloat duration = 4.f;
    CGFloat wholeWidth = screenWidth + CGRectGetWidth(self.bounds);

    //开始弹幕
    if (self.moveStausBlock) {
        self.moveStatusBlock(Start);
    }

    //t = s / v;
    CGFloat speed = wholeWidth/duration;
    CGFloat enterDuration = CGRectGetWidat(self.bounds)/speed;
    /*
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(enterDuration * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        if (self.moveStausBlock) {
            self.moveStatusBlock(Enter);
        }
    });
    */
    [self performSelector:@selector(enerScreen) withObject:nil afterDelay:enterDuration];
    //[NSObject cancelPreviousPerformRequestsWithTarget:self];

    __block CGRect frame = self.frame;
    [UIView animateWithDuration:duration delay:0 options:UIViewAnimationOptionCurveLinear animations:^{
        frame.origin.x -= wholeWidth;
        self.frame = frame;
    } completion:^(BOOL finished) {
        [self removeFromSuperview];
        
        if (self.moveStatusBlock) {
            self.moveStatusBlock(End);
        }
    }];
}

- (void)enterScreen {
    if (self.moveStatusBlock) {
        self.moveStatusBlock(Enter);
    }
}


//结束动画
- (void)stopAnimation {
    [NSObject cancelPreviousPerformRequestsWithTarget:self];
    [self.layer removeAllAnimations];
    [self removeFromSuperview];
}

- (UILabel *)lbComment {
    if (!_lbComment) {
        _lbComment = [[UILabel alloc] initWithFrame:CGRectZero];
        _lbComment.font = [UIFont systemFontOfSize:14];
        _lbComment.textColor = [UIColor whiteColor];
        _lbComment.textAlignment = NSTextAlignmentCenter;
        [self addSubview:_lbComment];
    }
    return _lbComment;
}
- (UIImageView *)photoIgv {
    if (!_photoIgv) {
        _photoIgv = [[UIImageView alloc] init];
        _photoIgv.layer.masksToBounds = YES;
        _hotoIgv.contentMode = UIViewContentModeScaleAspectFill;
        [self addSubview:_hotoIgv];
    }
    return bphotoIgv;
}

@end

#import <Foundation/Foundation.h>

@class BulletView;
@interface BulletManager: NSObject 

@property (nonatomic, copy) void(^generateViewBlock)(BulletView *view);

- (void)start;

- (void)stop;

@end

#import "BulletManager.h"
#import "BulletView.h"

@interface BulletManager ()

//弹幕的数据来源
@property (nonatomic, strong) NSMutableArray *datasource;
//弹幕使用过程中的数组变量
@property (nonatomic, strong) NSMutableArray *bulletComments;
//存储弹幕view的数组变量
@property (nonatomic, strong) NSMutableArray *bulletViews;

@property (nonatomic, assign) BOOL bStopAnimation;

@end

@implementation BulletManager 

- (void)start {
    [self.bulletComments removeAllObjects];
    [self.bulletComments addObjectsFromArray:self.datasource];
    [self initBulletComment];
}

- (void)stop {
    if (self.bStopAnimation) {
        return;
    }
    self.bStopAnimation = YES;
    [self.bulletViews enumerateObjectsUsingBlock:^(id _Nonnull obj, NSUInteger idx, BOOL * _Nonull stop){
        BulletView *view = obj;
        [view stopAnimation];
        view = nil;
    }];
    [self.bulletViews removeAllObjects];
}

//初始化弹幕，随即分配弹幕轨迹

- (void)initBulletComment {
    NSMutableArray *trajectorys = [NSMutableArray arrayWithArray:@[@0, @1, @2]];
    for (int i = 0; i < 3; i++) {
        if (self.bulletComments.count > 0) {
            //随即获取弹幕的轨迹
            NSInteger index = arc4random() % trajectorys.count;
            int trajectory = [trajectorys[index] intValue];

            //从弹幕数组逐一取出弹幕数据
            NSString *comment = [self.bulletComments firstObject];
            [self.bulletComments removeObjectAtIndex:0];

            //创建弹幕
            [self createBulletView:comment trajectory:trajectory];
        }   
    }
}

- (void)createBulletView:(NSString *)comment tragectory:(int)trajectory {
    if (self.bStopAnimation) { return; }
    BulletView *view = [[BulletView alloc] initWithComment:comment];
    view.trajectory = trajectory;

    __weak typeof (view) weakView = view;
    __weak typeof (self) weakSelf = self;
    view.moveStatusBlock = ^(MoveStatus status){

    if (self.bStopAnimation) { return; }
        switch (status) {
            case Start: {
                [weakSelf.bulletViews addObject:weakView];
                break;          
            }
            case Enter: {
                //判断是否有其余弹幕
                NSString *comment = [weakSelf nextComment];
                if (comment) {
                    [weakSelf createBulletView:comment trajectory:trajectory];
                }
                break;          
            }
            case End: {
                if([weakSelf.bulletViews containsObject:weakView]) {
                    //飞出释放资源
                    [weakView stopAnimation];
                    [weakSelf.bulletViews removeObject:weakView];
                }
                if (weakSelf.bulletViews.count == 0) {
                    //屏幕无弹幕 开始循环
                    self.bStopAnimation = YES;
                    [weakSelf start];
                }
                break;          
            }
            default: break;
        }

    //  [weakView stopAnimation];
    //  [weakSelf.bulletViews removeObject:weakView];
    };
    
    if (self.generateViewBlock) {
        self.generateViewBlock(weakView);
    }

}

- (NSString *)nextComment {
    if (self.bulletComments.count == 0) {
        return nil;
    }
    NSString *comment = [self.bulletComments firstObject];
    if (comment) {
        [self.bulletComments removeObjectAtIndex:0];
    }
    return comment;
}

- (NSMutableArray *)datasource {
    if (!_datasource) {
        _datasource = [NSMutableArray arrayWithArray:@[@"测试1", @"测试2", @"测试3", @"测试4", @"测试5", @"测试6", @"测试7", @"测试8"]];
    }
    return _datasource;
}

- (NSMutableArray *)bulletComments {
    if (!_bulletComments) {
        _bulletComments = [NSMutableArray array];
    }
    return _bulletComments;
}

- (NSMutableArray *)bulletViews {
    if (!_bulletViews) {
        _bulletViews = [NSMutableArray array];
    }
    return _bulletViews;
}

@end



//某viewController
#import "BulletManager.h"
#import "BulletView.h"

@property (nonatomic, strong) BulletManager *manager;

- (void)viewDidLoad {
    [super viewDidLoad];

    self.manager = [[BulletManager alloc] init];

    __weak typeof(self) weakSelf = self;
    self.manager.generateViewBlock = ^(BulletView *view) {
        [weakSelf addSubview:view]; 
    };

    UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];
    [btn setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
    [btn setTitle:@"start" forState:UIControlStateNormal];
    btn.frame = CGRectMake(100, 100, 100, 40);
    [btn addTarget:self action:@selector(clickBtn) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btn];

    [btn setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
    [btn setTitle:@"stop" forState:UIControlStateNormal];
    btn.frame = CGRectMake(250, 100, 100, 40);
    [btn addTarget:self action:@selector(clickStopBtn) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btn];
}

- (void)clickBtn {
    [self.manager start];
}

- (void)clickStopBtn {
    [self.manager stop];    
}
- (void)addBulletView:(BulletView *)view {
    CGFloat widath = [UIScreen mainScreen].bounds.size.width;
    view.frame = CGRectMake(width, 300 + view.trajectory * 50, CGRectGetWidth(view.bounds), CGRectGetHeight(view.bounds));
    [self.view addSubview:view];

    [view startAnimation];
}