CAEmitterLayer emits multiple CAEmitterCells with specified trajectories. When the trajectory CAEmitterCells fly to the end of time, it will become a particle graph displayed by CAEmitterCells, and then the particle graph will be scattered 360 °. However, only one trajectory particle can be animated completely, but more than two particles will appear. The trajectory particle graph will turn white Adding a boomEmitterCell will cause the contents of CAEmitterCell in getDogLeftDownEmitterWithImageName and getRedLeftEmitterWithImageName to not display the picture and white blocks CAEmitterLayer *emitterLayer = [[CAEmitterLayer alloc] init]; emitterLayer.emitterPosition = CGPointMake(self.view.layer.bounds.size.width -100, self.view.layer.bounds.size.height - 100); emitterLayer.emitterSize = CGSizeMake(50, 100.f); emitterLayer.emitterShape = kCAEmitterLayerLine; emitterLayer.emitterMode = kCAEmitterLayerOutline; emitterLayer.renderMode = kCAEmitterLayerOldestLast; CAEmitterCell *dogleftEmitterCell = [self getRedLeftEmitterWithImageName:[imageArray objectAtIndex:0]]; CAEmitterCell *redLeftEmitterCell = [self getRedLeftEmitterWithImageName:[imageArray objectAtIndex:0]]; emitterLayer.emitterCells = @[dogleftEmitterCell,redLeftEmitterCell]; [self.view.layer addSublayer:emitterLayer]; //狗头左下 - (CAEmitterCell *)getDogLeftDownEmitterWithImageName:(NSString *)imageName { CAEmitterCell *emitterCell = [[CAEmitterCell alloc] init]; emitterCell.name = @"左下狗头"; emitterCell.contents = (__bridge id _Nullable)[UIImage imageNamed:@"emoji_6"].CGImage; //产生频率 emitterCell.birthRate = 1; //存活时长 emitterCell.lifetime = 0.6; //速度 emitterCell.velocity = 100; emitterCell.xAcceleration = -1000.f; // 模拟重力影响 emitterCell.scale = 0.2; emitterCell.scaleSpeed = 0.25; emitterCell.emissionLongitude = M_PI_2; // emitterCell.emissionRange = M_PI_4; emitterCell.emitterCells = @[[self boomEmitterCell]]; return emitterCell; } //红包左上 - (CAEmitterCell *)getRedLeftEmitterWithImageName:(NSString *)imageName { CAEmitterCell *emitterCell = [[CAEmitterCell alloc] init]; emitterCell.name = @"红包"; emitterCell.contents = (__bridge id _Nullable)[UIImage imageNamed:@"emoji_7"].CGImage; //产生频率 emitterCell.birthRate = 10; //存活时长 emitterCell.lifetime = 0.6; // emitterCell.beginTime = self.beginTime; //速度 emitterCell.velocity = 100; emitterCell.yAcceleration = -1000.f; // 模拟重力影响 emitterCell.scale = 0.2; // emitterCell.scaleRange = 0.06; emitterCell.scaleSpeed = 0.25; emitterCell.emissionLongitude = M_PI; // CAEmitterCell *emitterCell = [self boomEmitterCell]; emitterCell.emitterCells = @[[self boomEmitterCell]]; return emitterCell; } - (CAEmitterCell *)boomEmitterCell { // 爆炸 CAEmitterCell * explodeCell = [CAEmitterCell emitterCell]; explodeCell.name = @"explodeCell"; explodeCell.birthRate = 2.f; explodeCell.lifetime = 0.6f; // explodeCell.velocity = 0.f; // explodeCell.scale = 1.0; // explodeCell.redSpeed = -1.5; //爆炸的时候变化颜色 // explodeCell.blueRange = 1.5; //爆炸的时候变化颜色 // explodeCell.greenRange = 1.f; //爆炸的时候变化颜色 // explodeCell.birthRate = 1.0; // explodeCell.velocity = 0; // explodeCell.scale = 2.5; // explodeCell.redSpeed =-1.5; // explodeCell.blueSpeed =+1.5; // explodeCell.greenSpeed =+1.0; // explodeCell.lifetime = 0.35; explodeCell.contents = (__bridge id _Nullable)[[UIImage imageNamed:@"allStart"] CGImage]; // 火花 // CAEmitterCell * sparkCell = [CAEmitterCell emitterCell]; // sparkCell.name = @"sparkCell"; // // sparkCell.birthRate = 3.f; // sparkCell.lifetime = 3.f; // sparkCell.velocity = 125.f; //// sparkCell.yAcceleration = 75.f; // 模拟重力影响 // sparkCell.emissionRange = M_PI * 2; // 360度 // // sparkCell.scale = 1.2f; // sparkCell.contents = (id)[[UIImage imageNamed:@"star_white_stroke"] CGImage]; // sparkCell.redSpeed = 0.4; // sparkCell.greenSpeed = -0.1; // sparkCell.blueSpeed = -0.1; // sparkCell.alphaSpeed = -0.25; // explodeCell.emitterCells = @[sparkCell]; return explodeCell; }

Due to the release of ProMotion devices, the system may switch frame rates in certain scenarios, resulting in the loss of reference value for data collected through CADisplayLink callbacks at a fixed 60Hz frame rate. We cannot distinguish whether the slow callback of CADisplayLink is due to a stutter or a system switch in frame rate. I know Hitch Time Ratio, but I can't use this scheme for some reasons. How can I distinguish between stuck and frame rate gear shift in CADisplaylink callback? In iOS 15, CADisplayLink.preferredFrameRateRange.preferred always returns 0, while minimum and maximum do change. Can I use these minimum and maximum range values as criteria to distinguish between frame rate switching and stuttering?