UITableView 头部效果/放大/移动跟随效果---- section圆角/阴影

 [self.tableView addObserver:self forKeyPath:@"contentOffset" options:NSKeyValueObservingOptionOld|NSKeyValueObservingOptionNew context:nil];

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context{
    CGPoint oldPoint = [change[@"old"] CGPointValue];
    CGPoint newPoint = [change[@"new"] CGPointValue];
//    NSLog(@"%@",change);
    CGFloat newY = newPoint.y;
    CGFloat oldY = oldPoint.y;
   if ( newY - oldY > 0) { //判断
        
        self.imageView.y -= newY;
        
        self.tableView.y = self.imageView.bottom;
        
        [self.tableView setContentOffset:CGPointMake(0, 0)];
     
    }
    else if (  newY - oldY < 0) {
//        self.imageView.y = self.imageView.y - newY;
//        if (self.imageView.y >= 0) {
//            self.imageView.y = 0;
//        }
//        self.tableView.y = self.imageView.bottom;
        self.imageView.y -= newY;
        
        self.tableView.y = self.imageView.bottom;
        
        [self.tableView setContentOffset:CGPointMake(0, 0)];

    }

}

https://github.com/yongliangP/YLSpringHeader

https://github.com/Cloudox/ScrollShowHeaderDemo

https://www.jianshu.com/p/8e4ed860d460

section 圆角 阴影

https://www.cnblogs.com/yeng/p/10540167.html

//===============Cell==================

@interface SubCell : UITableViewCell

@property (nonatomic, strong) SubCellShadowView *bgView;

@property (nonatomic, strong) NSIndexPath *indexPath;

@property (nonatomic) NSInteger rowInSection;//每一组的行数

@end

@implementation SubCell

- (void)awakeFromNib {

    [super awakeFromNib];

    self.selectionStyle = UITableViewCellSelectionStyleNone;

    self.clipsToBounds = NO;

 

    SubCellShadowView *bgView = [[SubCellShadowView alloc] init];

    [self insertSubview:bgView atIndex:0];

    self.bgView= bgView;

 

    CAShapeLayer *shadow = [CAShapeLayer layer];

    shadow.shadowColor = [UIColor blackColor].CGColor;

    shadow.shadowOffset=CGSizeMake(0,0);

    shadow.shadowOpacity=0.15;

    [bgView.layeraddSublayer:shadow];

    bgView.shadowLayer= shadow;

 

    CALayer*line = [CALayerlayer];

    line.backgroundColor = [UIColor groupTableViewBackgroundColor].CGColor;

    [bgView.layeraddSublayer:line];

    bgView.separatorLine= line;

}

-(void)layoutSubviews{

    [super layoutSubviews];

    UIBezierPath*bgBezierPath =nil;

    CGFloat cornerRaduis =7.0;//觉得阴影大的可以把半径调小,半径大的话阴影面积会变大

 

    if(self.indexPath.row==0 && self.rowInSection==1) {//单组单行

        self.bgView.clipsToBounds=NO;

        self.bgView.frame=self.bounds;

        CGRect rect = UIEdgeInsetsInsetRect(self.bgView.bounds, UIEdgeInsetsMake(0, 15, 0, 15));

        bgBezierPath = [UIBezierPath bezierPathWithRoundedRect:rect byRoundingCorners:UIRectCornerAllCorners cornerRadii:CGSizeMake(cornerRaduis, cornerRaduis)];

 

    }elseif(self.indexPath.row==0) {// 第一行

        self.bgView.clipsToBounds=YES;

        self.bgView.frame = UIEdgeInsetsInsetRect(self.bounds, UIEdgeInsetsMake(-5, 0, 0, 0));

        CGRect rect = UIEdgeInsetsInsetRect(self.bgView.bounds, UIEdgeInsetsMake(5, 15, 0, 15));

        bgBezierPath = [UIBezierPath bezierPathWithRoundedRect:rect byRoundingCorners:(UIRectCornerTopLeft|UIRectCornerTopRight) cornerRadii:CGSizeMake(cornerRaduis, cornerRaduis)];

 

    }elseif(self.indexPath.row==self.rowInSection-1) {// 最后一行

        self.bgView.clipsToBounds=YES;

        self.bgView.frame = UIEdgeInsetsInsetRect(self.bounds, UIEdgeInsetsMake(0, 0, -5, 0));

        CGRect rect = UIEdgeInsetsInsetRect(self.bgView.bounds, UIEdgeInsetsMake(0, 15, 5, 15));

        bgBezierPath = [UIBezierPath bezierPathWithRoundedRect:rect byRoundingCorners:(UIRectCornerBottomLeft|UIRectCornerBottomRight)  cornerRadii:CGSizeMake(cornerRaduis, cornerRaduis)];

 

    }else{// 中间行

        self.bgView.clipsToBounds=YES;

        self.bgView.frame = UIEdgeInsetsInsetRect(self.bounds, UIEdgeInsetsMake(0, 0, 0, 0));

        CGRect rect = UIEdgeInsetsInsetRect(self.bgView.bounds, UIEdgeInsetsMake(0, 15, 0, 15));

        bgBezierPath = [UIBezierPathbezierPathWithRect:rect];

 

    }

 

    self.bgView.shadowLayer.path= bgBezierPath.CGPath;

    self.bgView.shadowLayer.shadowPath= bgBezierPath.CGPath;

    self.bgView.shadowLayer.fillColor = [UIColor whiteColor].CGColor;

  

    //分割线 非单组单行 非最后一行

    if(!(self.indexPath.row==0&&self.rowInSection==1) && !(self.indexPath.row==self.rowInSection-1)) {

        self.bgView.separatorLine.frame = CGRectMake(self.bgView.frame.origin.x+30, self.bgView.frame.size.height-1, self.bgView.frame.size.width-30*2, 1.0);

    }

}

 

@end