前言 朋友问我设置UIScrollView的origin为(0,0)点，但是现实的效果是(0,StatusBar)，就是顶部空出了一个状态栏的高度。我就告诉他添加下面代码，能解决问题。
if (@available(iOS 11, *)) {
self.scrollView.contentInsetAdjustmentBehavior = UIScrollViewContentInsetAdjustmentNever;
} else {
self.automaticallyAdjustsScrollViewInsets = NO;
}
正好就一起扩展一下关于self.View 的(0,0)点的问题
接下来我们看这下面这3个属性
extendedLayoutIncludesOpaqueBarsedgesForExtendedLayoutautomaticallyAdjustsScrollViewInsets
1、extendedLayoutIncludesOpaqueBars
1.1如下代码：未设置导航栏的背景
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor redColor];
//默认导航栏是半透明的
// [self.navigationController.navigationBar setBackgroundImage:[UIImage imageNamed:@"t"] forBarMetrics:UIBarMetricsDefault];
NSLog(@"extendedLayoutIncludesOpaqueBars = %d",self.extendedLayoutIncludesOpaqueBars);
}
打印结果 ： extendedLayoutIncludesOpaqueBars = 0
未设置导航栏背景
1.2 给导航栏设置背景图
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor redColor];
[self.navigationController.navigationBar setBackgroundImage:[UIImage imageNamed:@"t"] forBarMetrics:UIBarMetricsDefault];
NSLog(@"extendedLayoutIncludesOpaqueBars = %d",self.extendedLayoutIncludesOpaqueBars);
}
打印结果：extendedLayoutIncludesOpaqueBars = 0
设置了导航栏背景
小结1：extendedLayoutIncludesOpaqueBars默认为NO，在导航栏为透明的时候，self.view 的(0,0)点，在屏幕的左上角，在导航栏不透明的时候，自动移到导航栏的下方，也就是(0,navigationBarHight)
1.3 导航栏未设置背景图，extendedLayoutIncludesOpaqueBars 赋值为YES
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor redColor];
self.extendedLayoutIncludesOpaqueBars = YES;
// [self.navigationController.navigationBar setBackgroundImage:[UIImage imageNamed:@"t"] forBarMetrics:UIBarMetricsDefault];
NSLog(@"extendedLayoutIncludesOpaqueBars = %d",self.extendedLayoutIncludesOpaqueBars);
}
打印结果：extendedLayoutIncludesOpaqueBars = 1
导航栏未设置背景图，extendedLayoutIncludesOpaqueBars 赋值为YES
1.4 导航栏设置背景图，extendedLayoutIncludesOpaqueBars 赋值为YES
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor redColor];
self.extendedLayoutIncludesOpaqueBars = YES;
[self.navigationController.navigationBar setBackgroundImage:[UIImage imageNamed:@"t"] forBarMetrics:UIBarMetricsDefault];
NSLog(@"extendedLayoutIncludesOpaqueBars = %d",self.extendedLayoutIncludesOpaqueBars);
}
打印结果：extendedLayoutIncludesOpaqueBars = 1
导航栏设置背景图，extendedLayoutIncludesOpaqueBars 赋值为YES
小结2：当设置 extendedLayoutIncludesOpaqueBars = YES的时候，不管导航栏是否透明，self.view的（0，0）点都是屏幕的左上角，我们在开发的时候最好设置为YES ，我们就统一计算frame，方便管理 tip:底部的tabbar也是和navigationBar是一样的道理
2、edgesForExtendedLayout ()
2.1edgesForExtendedLayout 设置为 UIRectEdgeAll(这也是默认值)
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor redColor];
self.edgesForExtendedLayout = UIRectEdgeAll;
}
UIRectEdgeAll
2.2 edgesForExtendedLayout 设置为 UIRectEdgeTop
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor redColor];
self.edgesForExtendedLayout = UIRectEdgeTop;
}
UIRectEdgeTop
2.3 edgesForExtendedLayout 设置为 UIRectEdgeBottom
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor redColor];
self.edgesForExtendedLayout = UIRectEdgeBottom;
}
UIRectEdgeBottom
2.4 edgesForExtendedLayout 设置为 UIRectEdgeNone
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor redColor];
self.edgesForExtendedLayout = UIRectEdgeNone;
}
UIRectEdgeNone
总结：通过设置edgesForExtendedLayout此属性，你可以指定view的边（上、下、左、右）延伸到整个屏幕。默认为UIRectEdgeAll
3、automaticallyAdjustsScrollViewInsets
automaticallyAdjustsScrollViewInsets（默认YES）这个属性在iOS11 已经被放弃使用了，使用UIScrollView的contentInsetAdjustmentBehavior
automaticallyAdjustsScrollViewInsets
所以我们在使用的时候要兼容老版本，代码如下:
if (@available(iOS 11, *)) {
self.tableView.contentInsetAdjustmentBehavior = UIScrollViewContentInsetAdjustmentNever;
} else {
self.automaticallyAdjustsScrollViewInsets = NO;
}
这个我就不写的Demo了
总结：开发的时候我们就设置 ,让（0，0）点在屏幕的左上角，方便计算frame self.extendedLayoutIncludesOpaqueBars = YES if (@available(iOS 11, *)) { self.tableView.contentInsetAdjustmentBehavior = UIScrollViewContentInsetAdjustmentNever; } else { self.automaticallyAdjustsScrollViewInsets = NO; }
