Ios 在UIButton周围创建一个CAShapeLayer？

我有一个UIButton，我想在它的内容之外创建一个边框

我想用CAShapeLayer或其他合适的方法创建它

我怎么能这样做呢

UIButton的borderColor和BorderWidth属性在按钮内部创建边框。宽度越大，从内部消耗的空间越大

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谢谢。

外面是什么意思？不能在远离按钮框的地方创建或添加任何内容。边框颜色/宽度在框架内完成，因此无法使其显示在远离框架的位置。

// This is the *.m file
 #import "ViewController.h"

 @interface ViewController ()

// Comment A. Another label and button added to the class without adding them to the
// storyboard
@property (nonatomic, strong) UIButton *firstButton;
 @end

@implementation ViewController

- (void)viewDidLoad
 {
[super viewDidLoad];

self.firstButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[self.firstButton setTitle:@"Just a Button" forState:UIControlStateNormal];
self.firstButton.frame = CGRectMake(50, 50, 300, 40);
UIGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(theAction:)];
[self.firstButton addGestureRecognizer:tapGesture];

//The screen width and height
CGRect screenBound = [[UIScreen mainScreen] bounds];
CGSize screenSize = screenBound.size;
CGFloat screenWidth = screenSize.width;
CGFloat screenHeight = screenSize.height;

//The CALayer definition
CALayer *graphic = nil;
graphic = [CALayer layer];
graphic.bounds = CGRectMake(0, 0, screenHeight, screenWidth);
graphic.position = CGPointMake(screenHeight/2, screenWidth/2);
graphic.backgroundColor = [UIColor whiteColor].CGColor;
graphic.opacity = 1.0f;
[graphic addSublayer:self.firstButton.layer];
[self.view.layer addSublayer:graphic];
}

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

- (IBAction)theAction:(id)sender {

NSLog(@"Button Tapped");
}
@end