6.6.7 弹幕

弹幕也是直播时比较常用的功能，实现起来也并不复杂，可以自己实现也可以借助一些优秀的开源库。这里我们选择了比较好的一个开源框架BarrageRenderer来完成弹幕功能。

实现步骤

1.引用

#import "BarrageRenderer.h"
#import "NSSafeObject.h"
@interface PullFlowViewController ()<BarrageRendererDelegate>{
}

2.初始化弹幕

- (void)initBarrageRenderer
{
    _renderer = [[BarrageRenderer alloc]init];
    _renderer.smoothness = .2f;
    _renderer.delegate = self;
    [_playerView addSubview:_renderer.view];
    _renderer.canvasMargin = UIEdgeInsetsMake(10, 10, 10, 10);
    // 若想为弹幕增加点击功能, 请添加此句话, 并在Descriptor中注入行为
    _renderer.view.userInteractionEnabled = YES;
    [_playerView sendSubviewToBack:_renderer.view];
}

3.绘制弹幕样式

- (BarrageDescriptor *)walkTextSpriteDescriptorWithDirection:(BarrageWalkDirection)direction
{
    return [self walkTextSpriteDescriptorWithDirection:direction side:BarrageWalkSideDefault];
}

- (BarrageDescriptor *)walkTextSpriteDescriptorWithDirection:(BarrageWalkDirection)direction side:(BarrageWalkSide)side
{
    BarrageDescriptor * descriptor = [[BarrageDescriptor alloc]init];
    descriptor.spriteName = NSStringFromClass([BarrageWalkTextSprite class]);
    descriptor.params[@"bizMsgId"] = [NSString stringWithFormat:@"%ld",(long)_index];
    //弹幕显示文字
    descriptor.params[@"text"] = [NSString stringWithFormat:@"过场文字弹幕:%ld",(long)_index++];
    descriptor.params[@"textColor"] = [UIColor whiteColor];
    descriptor.params[@"speed"] = @(100 * (double)random()/RAND_MAX+50);
    descriptor.params[@"direction"] = @(direction);
    descriptor.params[@"side"] = @(side);
    //点击弹幕提示，可以实现弹幕点赞功能
    descriptor.params[@"clickAction"] = ^(NSDictionary *params){
        NSString *msg = [NSString stringWithFormat:@"弹幕 %@ 被点击",params[@"bizMsgId"]];
        UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:@"提示" message:msg delegate:nil cancelButtonTitle:@"取消" otherButtonTitles:nil];
        [alertView show];
    };
    return descriptor;
}

弹幕显示方式

[_renderer receive:[self walkTextSpriteDescriptorWithDirection:BarrageWalkDirectionR2L side:BarrageWalkSideLeft]];
[_renderer receive:[self walkTextSpriteDescriptorWithDirection:BarrageWalkDirectionR2L side:BarrageWalkSideDefault]];

4.实现回调方法

- (void)barrageRenderer:(BarrageRenderer *)renderer spriteStage:(BarrageSpriteStage)stage spriteParams:(NSDictionary *)params
{
    NSString *subid = [params[@"identifier"] substringToIndex:8];
    if (stage == BarrageSpriteStageBegin) {
        NSLog(@"id:%@,bizMsgId:%@ =>进入",subid,params[@"bizMsgId"]);
    } else if (stage == BarrageSpriteStageEnd) {
        NSLog(@"id:%@,bizMsgId:%@ =>离开",subid,params[@"bizMsgId"]);
        /* 注释代码演示了如何复制一条弹幕
         BarrageDescriptor * descriptor = [[BarrageDescriptor alloc]init];
         descriptor.spriteName = NSStringFromClass([BarrageWalkTextSprite class]);
         [descriptor.params addEntriesFromDictionary:params];
         descriptor.params[@"delay"] = @(0);
         [renderer receive:descriptor];
         */
    }
}

5.开始弹幕

    [_renderer start];
    [_timer invalidate];
    NSSafeObject * safeObj = [[NSSafeObject alloc]initWithObject:self withSelector:@selector(autoSendBarrage)];
    _timer = [NSTimer scheduledTimerWithTimeInterval:0.5 target:safeObj selector:@selector(excute) userInfo:nil repeats:YES];

6.结束弹幕

    [_renderer stop];

实现效果

实现效果如图6-15所示

图6-15