iOS中全局悬浮按钮，类似IPhone中的AssistiveTouch （可以替换为视频悬浮窗口）

前提：当时看到别人写过这个类似AssistiveTouch的demo，但是有问题，第一改变不了位置、第二切换页面后无法使用、第三运行时偶尔会崩溃。然后自己就去度娘、论坛中都查了一些资料，然后结合起来写了这么一个demo。
思路：实现全局 需要在 AppDelegate.m 文件中 didFinishLaunchingWithOptions 方法里面实现
1、新建一个 继承于 UIWindow 的类 AssistiveTouch

//在 AssistiveTouch.h 文件中代码

#import <UIKit/UIKit.h>

@interface AssistiveView :UIWindow

{

    UIButton *_button;

}

-(id) initWithFrame:(CGRect)frame;

@end

//在 AssistiveTouch.m 文件中代码

#import "AssistiveView.h"

@implementation AssistiveView

/*

// Only override drawRect: if you perform custom drawing.

// An empty implementation adversely affects performance during animation.

- (void)drawRect:(CGRect)rect {

    // Drawing code

}

*/

-(id)initWithFrame:(CGRect)frame

{

    self = [superinitWithFrame:frame];

    

    if (self) {

        self.backgroundColor = [UIColorclearColor];

        self.windowLevel =UIWindowLevelAlert + 1;

        //这句话很重要

        [selfmakeKeyAndVisible];

        

        _button = [UIButtonbuttonWithType:UIButtonTypeCustom];

        _button.backgroundColor = [UIColorgrayColor];

        _button.frame =CGRectMake(0,0, frame.size.width, frame.size.height);

        _button.layer.cornerRadius = frame.size.width/2;

        [_buttonaddTarget:selfaction:@selector(choose)forControlEvents:UIControlEventTouchUpInside];

        [selfaddSubview:_button];

        

       //放一个拖动手势，用来改变控件的位置

        UIPanGestureRecognizer *pan = [[UIPanGestureRecognizeralloc] initWithTarget:selfaction:@selector(changePostion:)];

        [_buttonaddGestureRecognizer:pan];

    }

    returnself;

}

//按钮事件

-(void)choose

{

    NSLog(@"悬浮窗");

}

//手势事件－－改变位置

-(void)changePostion:(UIPanGestureRecognizer *)pan

{

    CGPoint point = [pantranslationInView:self];

    

    CGFloat width = [UIScreenmainScreen].bounds.size.width;

    CGFloat height = [UIScreenmainScreen].bounds.size.height;

    

    CGRect originalFrame =self.frame;

    if (originalFrame.origin.x >=0 && originalFrame.origin.x+originalFrame.size.width <= width) {

        originalFrame.origin.x += point.x;

    }

    if (originalFrame.origin.y >=0 && originalFrame.origin.y+originalFrame.size.height <= height) {

        originalFrame.origin.y += point.y;

    }

    self.frame = originalFrame;

    [pan setTranslation:CGPointZeroinView:self];

    

    if (pan.state ==UIGestureRecognizerStateBegan) {

        _button.enabled =NO;

    }elseif (pan.state ==UIGestureRecognizerStateChanged){

        

    } else {

        

        CGRect frame =self.frame;

        //记录是否越界

        BOOL isOver =NO;

        

        if (frame.origin.x <0) {

            frame.origin.x =0;

            isOver = YES;

        } elseif (frame.origin.x+frame.size.width > width) {

            frame.origin.x = width - frame.size.width;

            isOver = YES;

        }

        

        if (frame.origin.y <0) {

            frame.origin.y =0;

            isOver = YES;

        } elseif (frame.origin.y+frame.size.height > height) {

            frame.origin.y = height - frame.size.height;

            isOver = YES;

        }

        if (isOver) {

            [UIViewanimateWithDuration:0.3animations:^{

                self.frame = frame;

            }];

        }

        _button.enabled =YES;

    }

}

//在AppDelegate中的代码

#import "AppDelegate.h"

#import "AssistiveView.h"

@interfaceAppDelegate ()

{

    //悬浮框

    AssistiveView * _Win;

}

@end

@implementation AppDelegate

//设置自定义悬浮框坐标

-(void)setNew

{

    _Win = [[AssistiveViewalloc] initWithFrame:CGRectMake(0,100, 60,60)];

}

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

    // Override point for customization after application launch.

    

   // 这句话很重要，要先将rootview加载完成之后在显示悬浮框，如没有这句话，将可能造成程序崩溃

    [selfperformSelector:@selector(setNew)withObject:nilafterDelay:3];

    

    [self.windowmakeKeyAndVisible];

    

    returnYES;

}