iOS开发——实战技术OC篇&点击状态栏ScrollView（包括子控件）自动滚到顶部

 1 import UIKit
 2 class TopWindow: UIWindow {
 3     private static let window_: UIWindow = UIWindow()
 4     ///  类初始化方法,保证window_只被创建一次
 5     override class func initialize() {
 6         window_.frame = CGRectMake(0, 0, global.appWidth, 20)
 7         window_.windowLevel = UIWindowLevelAlert
 8         window_.addGestureRecognizer(UITapGestureRecognizer(target: self, action: "topWindowClick"))
 9     }
10     class func topWindowClick() {
11         // 遍历当前主窗口所有view,将满足条件的scrollView滚动回原位
12         searchAllowScrollViewInView(UIApplication.sharedApplication().keyWindow!)
13     }
14     private class func searchAllowScrollViewInView(superView: UIView) {
15         for subview: UIView in superView.subviews as! [UIView] {
16             if subview.isKindOfClass(UIScrollView.self) && superView.viewIsInKeyWindow() {
17                 // 拿到scrollView的contentOffset
18                 var offest = (subview as! UIScrollView).contentOffset
19                 // 将offest的y轴还原成最开始的值
20                 offest.y = -(subview as! UIScrollView).contentInset.top
21                 // 重新设置scrollView的内容
22                 (subview as! UIScrollView).setContentOffset(offest, animated: true)
23             }
24             // 递归,让子控件再次调用这个方法判断时候还有满足条件的view
25             searchAllowScrollViewInView(subview)
26         }
27     }
28     ///  添加topWindow,使手势生效
29     class func showTopWindow() {
30         window_.hidden = false
31     }
32     ///  隐藏topWindow,移除手势
33     class func hiddenTopWindow() {
34         window_.hidden = true
35     }
36 }
37 ///  对UIView的一个扩展
38 extension UIView {
39     ///  判断调用方法的view是否在keyWindow中
40     func viewIsInKeyWindow() -> Bool {
41         let keyWindow = UIApplication.sharedApplication().keyWindow!
42         // 将当前view的坐标系转换到window.bounds
43         let viewNewFrame = keyWindow.convertRect(self.frame, fromView: self.superview)
44         let keyWindowBounds = keyWindow.bounds
45         // 判断当前view是否在keyWindow的范围内
46         let isIntersects = CGRectIntersectsRect(viewNewFrame, keyWindowBounds)
47         // 判断是否满足所有条件
48         return !self.hidden && self.alpha > 0.01 && self.window == keyWindow && isIntersects
49     }
50 }

1 func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
2     // 添加顶部的window
3     TopWindow.showTopWindow()
4     return true
5   }

1  @interface WNXTopWindow : NSObject
2 + (void)show;
3 + (void)hide;
4 @end

 1 #import "WNXTopWindow.h"
 2 @implementation WNXTopWindow
 3 static UIWindow *window_;
 4 //初始化window
 5 + (void)initialize {
 6     window_ = [[UIWindow alloc] init];
 7     window_.frame = CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, 20);
 8     window_.windowLevel = UIWindowLevelAlert;
 9     [window_ addGestureRecognizer:[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(windowClick)]];
10 }
11 + (void)show {
12     window_.hidden = NO;
13 }
14 + (void)hide {
15     window_.hidden = YES;
16 }
17 // 监听窗口点击
18 + (void)windowClick {
19     UIWindow *window = [UIApplication sharedApplication].keyWindow;
20     [self searchScrollViewInView:window];
21 }
22 + (void)searchScrollViewInView:(UIView *)superview {
23     for (UIScrollView *subview in superview.subviews) {
24         // 如果是scrollview, 滚动最顶部
25         if ([subview isKindOfClass:[UIScrollView class]] && [subview isShowingOnKeyWindow]) {
26             CGPoint offset = subview.contentOffset;
27             offset.y = - subview.contentInset.top;
28             [subview setContentOffset:offset animated:YES];
29         }
30         // 递归继续查找子控件
31         [self searchScrollViewInView:subview];
32     }
33 }
34 + (BOOL)isShowingOnKeyWindow:(UIView *)view {
35     // 主窗口
36     UIWindow *keyWindow = [UIApplication sharedApplication].keyWindow;
37     // 以主窗口左上角为坐标原点, 计算self的矩形框
38     CGRect newFrame = [keyWindow convertRect:view.frame fromView:view.superview];
39     CGRect winBounds = keyWindow.bounds;
40     // 主窗口的bounds 和 self的矩形框 是否有重叠
41     BOOL intersects = CGRectIntersectsRect(newFrame, winBounds);
42     return !view.isHidden && view.alpha > 0.01 && view.window == keyWindow && intersects;
43 }
44 @end
45 同样,也是在程序初始化完成AppDelegate文件中显示topWindow,整个工程这个问题就统统解决了
46 
47 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
48     // 添加一个window, 点击这个window, 可以让屏幕上的scrollView滚到最顶部
49     [WNXTopWindow show];
50     return YES;
51 }