当触摸内部时，IOS UIButton的尺寸变大

Question

简单代码..

ViewController.h

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController
- (IBAction)dragout:(id)sender;

@end

ViewController.m

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (IBAction)dragout:(id)sender {
    NSLog(@"-----");
}
@end

在Storyboard中，有1个按钮，其大小适合文本“按钮”。链接'发送事件：触摸拖动外部“到”拖出“IBAction。

当我触摸内部按钮并将手指拖到按钮外部时，我需要移动多于按钮大小来调用“拖出”IBAction。近3倍的宽度和高度尺寸。为什么会这样？请阅读。