How to add UIButton on WKWebview? - ios

Question

I have two viewcontrollers which the viewcontroller1 has a NSTimer countdown to 0 and present viewcontroller2.
The viewcontroller2 has a wkwebview, and I also want to add UIButton on it.
Because I want to create a close button to dismiss viewcontroller2.
I try adding the UIButton on wkwebview, but I can't control it's NSlayoutConstrain.
What's wrong with my code?
Thanks.
red button is on right bottom.
// ViewController1.m
-(void)timerFired {
NSLog(#"===) self.count : %d", self.count);
if (self.count == 0) {
[self.timer invalidate];
self.timer = nil;
ViewController2 *vc = [[ViewController2 alloc] init];
[self presentViewController:vc animated:YES completion:nil];
} else {
self.count -= 1;
}
}
// ViewController2.m
#import "ViewController2.h"
#import <WebKit/WebKit.h>
#interface ViewController2 ()<WKScriptMessageHandler, WKNavigationDelegate,WKUIDelegate>
#property (nonatomic,strong) WKWebView* webView;
#property (nonatomic,strong) UIButton* button;
#property (nonatomic, strong) WKWebViewConfiguration * webConfig;
#end
#implementation ViewController2
- (void)viewDidLoad {
[super viewDidLoad];
self.webView = [[WKWebView alloc] initWithFrame:self.view.frame configuration:[self createWKWebApp]];
[self.view addSubview: self.webView];
[self.webView.configuration.preferences setValue:#YES forKey:#"allowFileAccessFromFileURLs"];
self.webView.scrollView.bounces = NO;
[self.webView setContentMode:UIViewContentModeScaleAspectFit];
self.webView.navigationDelegate = self;
self.webView.UIDelegate = self;
NSURL *url = [NSURL URLWithString:#"https://stackoverflow.com/"];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
[self.webView loadRequest:request];
self.button = [UIButton buttonWithType: UIButtonTypeCustom];
self.button.translatesAutoresizingMaskIntoConstraints = false;
self.button.backgroundColor = UIColor.redColor;
[self.button setTitle:#"CLOSE" forState:UIControlStateNormal];
[self.button addTarget:self action:#selector(btnClicked:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:self.button];
NSLayoutConstraint *btnRight = [NSLayoutConstraint constraintWithItem:self.button attribute:NSLayoutAttributeRight relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeRight multiplier:1.0 constant:-20.0];
NSLayoutConstraint *btnTop = [NSLayoutConstraint constraintWithItem:self.button attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeBottom multiplier:1.0 constant:20.0];
NSLayoutConstraint *btnWidth = [NSLayoutConstraint constraintWithItem:self.button attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeWidth multiplier:1.0 constant:30.0];
NSLayoutConstraint *btnHeight = [NSLayoutConstraint constraintWithItem:self.button attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeHeight multiplier:1.0 constant:30.0];
[self.view addConstraints:#[btnRight, btnTop, btnWidth, btnHeight]];
}
- (void)btnClicked:(UIButton *)sender {
NSLog(#"BTN CLICKED");
[self dismissViewControllerAnimated:false completion:nil];
}
- (WKWebViewConfiguration *)createWKWebApp {
WKWebViewConfiguration *config = [[WKWebViewConfiguration alloc] init];
WKUserContentController *userContent = [[WKUserContentController alloc] init];
config.userContentController = userContent;
return config;
}
- (void)userContentController:(WKUserContentController*)userContentController didReceiveScriptMessage:(WKScriptMessage*)message {
NSString *name = message.name;
NSLog(#"===) message name = %#",name);
NSLog(#"===) body class = %#",[message.body class]);
}

Answer 1

You should konw the constraint like this
item1.attribute1 = multiplier × item2.attribute2 + constant
So the right constraint constant should be -20
NSLayoutConstraint *btnRight = [NSLayoutConstraint constraintWithItem:self.button attribute:NSLayoutAttributeRight relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeRight multiplier:1.0 constant:-20.0];

Answer 2

It might help you. Use these methods.
-(void)view.sendSubviewToBack(subview)
-(void)view.bringSubviewToFront(subview)
Usage:
[self.view sendSubviewToBack:webview];
[self.view bringSubviewToFront:button];