iOS中全局悬浮按钮，类似IPhone中的AssistiveTouch

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 AssistiveTouch : UIWindow
{
UIButton *_button;
}

-(id) initWithFrame:(CGRect)frame;

@end

//在 AssistiveTouch.m 文件中代码

#import "AssistiveTouch.h"

@interface AssistiveTouch ()

@end

@implementation AssistiveTouch

/*
// 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 = [super initWithFrame:frame];

if (self) {
self.backgroundColor = [UIColor clearColor];
self.windowLevel = UIWindowLevelAlert + 1;
//这句话很重要
[self makeKeyAndVisible];

_button = [UIButton buttonWithType:UIButtonTypeCustom];
_button.backgroundColor = [UIColor grayColor];
_button.frame = CGRectMake(0, 0, frame.size.width, frame.size.height);
_button.layer.cornerRadius = frame.size.width/2;
[_button addTarget:self action:@selector(choose) forControlEvents:UIControlEventTouchUpInside];
[self addSubview:_button];

//放一个拖动手势，用来改变控件的位置
UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(changePostion:)];
[_button addGestureRecognizer:pan];
}
return self;
}

//按钮事件
-(void)choose
{
NSLog(@"悬浮窗");
}
//手势事件 －－ 改变位置
-(void)changePostion:(UIPanGestureRecognizer *)pan
{
CGPoint point = [pan translationInView:self];

CGFloat width = [UIScreen mainScreen].bounds.size.width;
CGFloat height = [UIScreen mainScreen].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:CGPointZero inView:self];

if (pan.state == UIGestureRecognizerStateBegan) {
_button.enabled = NO;
}else if (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;
} else if (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;
} else if (frame.origin.y+frame.size.height > height) {
frame.origin.y = height - frame.size.height;
isOver = YES;
}
if (isOver) {
[UIView animateWithDuration:0.3 animations:^{
self.frame = frame;
}];
}
_button.enabled = YES;
}
}

@end

#import "AppDelegate.h"
#import "AssistiveTouch.h"

@interface AppDelegate ()
{
//悬浮框
AssistiveTouch * _Win;
}
@end

@implementation AppDelegate

// 设置自定义悬浮框坐标
-(void)setNew
{
_Win = [[AssistiveTouch alloc] initWithFrame:CGRectMake(0, 0, 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
[self performSelector:@selector(setNew) withObject:nil afterDelay:3];

[self.window makeKeyAndVisible];

return YES;
}