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这篇文章主要介绍iOS中tableView如何实现头部拉伸并改变导航条渐变色，文中介绍的非常详细，具有一定的参考价值，感兴趣的小伙伴们一定要看完！
具体内容如下
#import "TableViewController.h"
static NSString *ident = @"cell";
#define RGBA(r,g,b,a) [UIColor colorWithRed:r/255.0f green:g/255.0f blue:b/255.0f alpha:a]
#define RGB(r,g,b) RGBA(r,g,b,1.0f)
#define ZhuTiColor RGB(76,16,198)
#define ZhuTiColorAlpha(alpha) RGBA(76, 16, 198, alpha)
// 判断是否是iPhone X
#define iPhoneX ([UIScreen instancesRespondToSelector:@selector(currentMode)] ? CGSizeEqualToSize(CGSizeMake(1125, 2436), [[UIScreen mainScreen] currentMode].size) : NO)
// 状态栏高度
#define STATUS_BAR_HEIGHT (iPhoneX ? 44.f : 20.f)
// 导航栏高度
#define NAVIGATION_BAR_HEIGHT (iPhoneX ? 88.f : 64.f)
// tabBar高度
#define TAB_BAR_HEIGHT (iPhoneX ? (49.f + 34.f) : 49.f)
// home indicator
#define HOME_INDICATOR_HEIGHT (iPhoneX ? 34.f : 0.f)
#define ScreenWidth ([UIScreen mainScreen].bounds.size.width)
#define ScreenHeight ([UIScreen mainScreen].bounds.size.height)
#define imageHight 200
@interface TableViewController ()
@property (nonatomic,strong) UIImageView *headImage;
@property (nonatomic, strong) UIView *headerBackView;
@property (nonatomic, strong) UIView *mengView;
@end
@implementation TableViewController
- (void)viewDidLoad {
[super viewDidLoad];
[self.tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:ident];
self.view.backgroundColor = [UIColor redColor];
self.tableView.tableHeaderView = self.headerBackView;
[self.headerBackView addSubview:self.headImage];
[self.headImage addSubview:self.mengView];
[self navCleanFromAlpha:0];
}
-(void)navCleanFromAlpha:(CGFloat)alpha
{
[self.navigationController.navigationBar setBackgroundImage:[self createImageWithColor:ZhuTiColorAlpha(alpha)] forBarMetrics:UIBarMetricsDefault];
self.navigationController.navigationBar.shadowImage = [UIImage new];
}
-(UIImage*) createImageWithColor:(UIColor*) color
{
CGRect rect=CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, [color CGColor]);
CGContextFillRect(context, rect);
UIImage *theImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return theImage;
}
-(UIImageView *)headImage
{
if(!_headImage)
{
_headImage= [[UIImageView alloc]initWithFrame: self.headerBackView.bounds];
_headImage.image = [UIImage imageNamed:@"1024"];
}
return _headImage;
}
-(UIView *)mengView
{
if (!_mengView)
{
_mengView = [[UIView alloc]initWithFrame:self.headerBackView.bounds];
_mengView.backgroundColor = RGBA(1, 1, 1, 0.1);
}
return _mengView;
}
-(UIView *)headerBackView
{
if (!_headerBackView)
{
_headerBackView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, ScreenWidth, imageHight)];
[_headerBackView setBackgroundColor:[UIColor lightGrayColor]];
}
return _headerBackView;
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
//---------------------- 图片拉升 -------------------------
//图片高度
CGFloat imageHeight = self.headerBackView.frame.size.height;
//图片宽度
CGFloat imageWidth = ScreenWidth;
//图片上下偏移量
CGFloat imageOffsetY = scrollView.contentOffset.y;
// NSLog(@"图片上下偏移量 imageOffsetY:%f ->",imageOffsetY);
//上移
if (imageOffsetY < 0)
{
CGFloat totalOffset = imageHeight + ABS(imageOffsetY);
CGFloat f = totalOffset / imageHeight;
self.headImage.frame = CGRectMake(-(imageWidth * f - imageWidth) * 0.5, imageOffsetY, imageWidth * f, totalOffset);
self.mengView.frame = self.headImage.bounds;
}
//------------------- 导航条颜色渐变 ----------------------------
CGFloat tableViewOffsetY = [self.tableView rectForSection:0].origin.y - NAVIGATION_BAR_HEIGHT;
CGFloat contentOffsetY = scrollView.contentOffset.y;
if (contentOffsetY >= tableViewOffsetY)
{
// scrollView.contentOffset = CGPointMake(0, tableViewOffsetY); //定位
[self navCleanFromAlpha:1];
}
else
{
CGFloat alpha = scrollView.contentOffset.y/imageHight;
if (alpha >= 1) { alpha = 1; }
if (alpha <= 0) { alpha = 0; }
NSLog(@"%.2f",alpha);
[self navCleanFromAlpha:alpha];
}
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return 20;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:ident forIndexPath:indexPath];
// Configure the cell...
cell.textLabel.text = [NSString stringWithFormat:@"asdada = %zd",indexPath.row];
return cell;
}以上是“iOS中tableView如何实现头部拉伸并改变导航条渐变色”这篇文章的所有内容，感谢各位的阅读！希望分享的内容对大家有帮助，更多相关知识，欢迎关注创新互联网站建设公司行业资讯频道！
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