效果

IMG_CFC06192E39E-2.jpeg

#import <QuartzCore/QuartzCore.h>

NS_ASSUME_NONNULL_BEGIN

@interface ScanLayer : CAShapeLayer

+ (instancetype)layerWithFrame:(CGRect)frame;

- (void)stopRun;

@end

NS_ASSUME_NONNULL_END

#import "ScanLayer.h"
#import <UIKit/UIKit.h>

@interface ScanLayer ()

@property (nonatomic, strong) CAShapeLayer *layer;

@end

@implementation ScanLayer

+ (instancetype)layerWithFrame:(CGRect)frame
{
    ScanLayer *l = [super layer];
    if (l) {
        l.frame = frame;
        l.masksToBounds = YES;
        l.backgroundColor = [UIColor clearColor].CGColor;
        [l draw];
    }
    return l;
}

- (void)draw
{
    CGFloat w = 8;
    CGFloat h = 8;
    NSInteger indexW = (NSInteger)self.frame.size.width/w + 1;
    NSInteger indexH = (NSInteger)self.frame.size.height/h + 1;
    
    UIBezierPath *path = [UIBezierPath bezierPath];
    for (int i = 0; i < indexW; i++) {
        UIBezierPath *path1 = [UIBezierPath bezierPath];
        [path1 moveToPoint:CGPointMake(h * i, 0)];
        [path1 addLineToPoint:CGPointMake(h * i, self.frame.size.height)];
        [path appendPath:path1];
    }
    for (int j = 0; j < indexH; j++) {
        UIBezierPath *path1 = [UIBezierPath bezierPath];
        [path1 moveToPoint:CGPointMake(0, w * j)];
        [path1 addLineToPoint:CGPointMake(self.frame.size.width, w * j)];
        [path appendPath:path1];
    }
    self.layer = [CAShapeLayer layer];
    self.layer.frame = self.bounds;
    self.layer.path = path.CGPath;
    self.layer.lineWidth = 1;
    self.layer.strokeColor = [UIColor greenColor].CGColor;
    self.layer.fillColor = [UIColor clearColor].CGColor;
    [self addSublayer:self.layer];

    
    CABasicAnimation *anim = [CABasicAnimation animationWithKeyPath:@"transform.translation.y"];
    anim.fromValue = @(-self.frame.size.height);
    anim.toValue = @(0);
    anim.repeatCount = MAXFLOAT;
    anim.duration = 1.0;
    anim.fillMode = kCAFillModeForwards;
    anim.removedOnCompletion = NO;
    anim.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
    
    CABasicAnimation *anim1 = [CABasicAnimation animationWithKeyPath:@"opacity"];
    anim1.fromValue = @1;
    anim1.toValue = @(0);
    anim1.repeatCount = MAXFLOAT;
    anim1.duration = 1.0;
    anim1.fillMode = kCAFillModeForwards;
    anim1.removedOnCompletion = NO;
    anim1.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
    
    CAAnimationGroup *group = [CAAnimationGroup animation];
    group.animations = @[anim,anim1];
    group.repeatCount = MAXFLOAT;
    group.duration = 1.0;
    group.fillMode = kCAFillModeForwards;
    group.removedOnCompletion = NO;
    [self.layer addAnimation:group forKey:@"anim"];
    
}

- (void)stopRun
{
    [self.layer removeAllAnimations];
}

@end