A self contained UINavigationViewController and UIViewController for presenting a WKWebView on iOS 8

PRSModalWebViewController.h

#import <WebKit/WebKit.h>


@protocol PRSProgressDelegate <NSObject>

- (void)setNavigationTitle:(NSString *)title;
- (void)setProgress:(CGFloat)progress animated:(BOOL)animated;
- (void)setVisible:(BOOL)visible animated:(BOOL)animated;

@end



typedef void(^PRSControllerDismissBlock)(UIViewController *viewController);



@interface PRSModalWebViewController : UINavigationController <PRSProgressDelegate>

- (instancetype)initWithURL:(NSURL *)URL dismissBlock:(PRSControllerDismissBlock)block;

@end



@interface PRSProgressNavigationBar : UINavigationBar

- (void)setProgressBarColor:(UIColor *)color;
- (void)setProgressBarVisible:(BOOL)visible aniamted:(BOOL)animated;

- (void)setProgress:(CGFloat)progress animated:(BOOL)animated;

@end



@interface PRSWebViewController : UIViewController

@property (nonatomic, readonly) WKWebView *webView;

- (instancetype)initWithURL:(NSURL *)URL progressDelegate:(id<PRSProgressDelegate>)delegate dismissBlock:(PRSControllerDismissBlock)block;

@end

PRSModalWebViewController.m

#import "PRSModalWebViewController.h"


@class PRSWebViewController;

@interface PRSModalWebViewController ()
@property (nonatomic, strong) PRSWebViewController *webViewController;

@property (nonatomic, readonly) PRSProgressNavigationBar *progressNavigationBar;

@end

@implementation PRSModalWebViewController


- (instancetype)initWithURL:(NSURL *)URL dismissBlock:(PRSControllerDismissBlock)block
{
    if (self = [super initWithNavigationBarClass:[PRSProgressNavigationBar class] toolbarClass:nil]) {
        self.webViewController = [[PRSWebViewController alloc] initWithURL:URL progressDelegate:self dismissBlock:block];
    }
    
    return self;
}

- (PRSProgressNavigationBar *)progressNavigationBar
{
    if ([self.navigationBar isKindOfClass:[PRSProgressNavigationBar class]]) {
        return (PRSProgressNavigationBar *)self.navigationBar;
    }
    
    return nil;
}


- (void)setNavigationTitle:(NSString *)title
{
    self.webViewController.title = title;
}


- (void)setProgress:(CGFloat)progress animated:(BOOL)animated
{
    [self.progressNavigationBar setProgress:progress animated:animated];
}

- (void)setVisible:(BOOL)visible animated:(BOOL)animated
{
    [self.progressNavigationBar setProgressBarVisible:visible aniamted:animated];
}


- (void)viewDidLoad
{
    [super viewDidLoad];
    [self.progressNavigationBar setProgressBarColor:[UIColor redColor]];
}


@end



static void * PRSWebViewControllerContext = &PRSWebViewControllerContext;

@interface PRSWebViewController ()

@property (nonatomic, readwrite) WKWebView *webView;

@property (nonatomic) NSURL *initialURL;
@property (nonatomic, weak) id<PRSProgressDelegate> progressDelegate;
@property (nonatomic, copy) PRSControllerDismissBlock dismissBlock;

@end


@implementation PRSWebViewController

- (instancetype)initWithURL:(NSURL *)URL progressDelegate:(id<PRSProgressDelegate>)delegate dismissBlock:(PRSControllerDismissBlock)block
{
    if (self = [super init]) {
        _initialURL = URL;
        _progressDelegate = delegate;
        _dismissBlock = block;
    }
    
    return self;
}


- (void)registerObservers
{
    [self.webView addObserver:self forKeyPath:PropertyKey(title) options:NSKeyValueObservingOptionNew context:PRSWebViewControllerContext];
    [self.webView addObserver:self forKeyPath:PropertyKey(estimatedProgress) options:NSKeyValueObservingOptionNew context:PRSWebViewControllerContext];
    [self.webView addObserver:self forKeyPath:@"loading" options:NSKeyValueObservingOptionNew context:PRSWebViewControllerContext];
}

- (void)unregisterObservers
{
    [self.webView removeObserver:self forKeyPath:PropertyKey(title) context:PRSWebViewControllerContext];
    [self.webView removeObserver:self forKeyPath:PropertyKey(estimatedProgress) context:PRSWebViewControllerContext];
    [self.webView removeObserver:self forKeyPath:@"loading" context:PRSWebViewControllerContext];
}



- (void)viewDidLoad
{
    [super viewDidLoad];
    
    self.webView = [[WKWebView alloc] initWithFrame:self.view.bounds];
    [self.view addSubview:self.webView];
    
    UIBarButtonItem *back = [[UIBarButtonItem alloc] initWithTitle:@"Back" style:UIBarButtonItemStylePlain target:self.webView action:@selector(goBack)];
    UIBarButtonItem *forward = [[UIBarButtonItem alloc] initWithTitle:@"Forward" style:UIBarButtonItemStylePlain target:self.webView action:@selector(goForward)];
    UIBarButtonItem *close = [[UIBarButtonItem alloc] initWithTitle:@"Close" style:UIBarButtonItemStyleDone target:self action:@selector(close)];
    UIBarButtonItem *flexibleSpace = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];
    UIBarButtonItem *space = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil];

    self.navigationController.toolbarHidden = NO;
    self.navigationController.toolbarItems = @[back, forward];
    
    self.webView.allowsBackForwardNavigationGestures = YES;
    
    [self registerObservers];
}


- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    
    if (self.initialURL) {
        [self.webView loadRequest:[NSURLRequest requestWithURL:self.initialURL]];
        [self.progressDelegate setNavigationTitle:self.initialURL.absoluteString];
    }
}


- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
    if (context == PRSWebViewControllerContext) {
        if ([keyPath isEqualToString:PropertyKey(title)]) {
            NSString *title = change[NSKeyValueChangeNewKey];
            [self.progressDelegate setNavigationTitle:title];
            
        } else if ([keyPath isEqualToString:PropertyKey(estimatedProgress)]) {
            double estimatedProgress = [change[NSKeyValueChangeNewKey] doubleValue];
//            NSLog(@"KVO - estimatedProgress: %@", @(estimatedProgress));
            [self.progressDelegate setProgress:estimatedProgress animated:YES];
            
        } else if ([keyPath isEqualToString:@"loading"]) {
            BOOL loading = [change[NSKeyValueChangeNewKey] boolValue];
            NSLog(@"KVO - loading: %@", @(loading));
            [self.progressDelegate setVisible:loading animated:YES];
            
        }
    } else {
        [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
    }
}


- (void)close
{
    __weak typeof(self) welf = self;
    [self dismissViewControllerAnimated:YES completion:^{
        typeof(welf) strongSelf = welf;
        if (strongSelf && strongSelf.dismissBlock) {
            strongSelf.dismissBlock(strongSelf);
        }
        
    }];
}

- (void)dealloc
{
    [self unregisterObservers];
}

@end



@interface PRSProgressNavigationBar ()

@property (nonatomic, strong) UIProgressView *progressView;
@property (nonatomic, getter = isVisible) BOOL visible;

@end


@implementation PRSProgressNavigationBar

- (instancetype)initWithFrame:(CGRect)frame
{
    if (self = [super initWithFrame:frame]) {
        _progressView = [[UIProgressView alloc] initWithProgressViewStyle:UIProgressViewStyleBar];
        _progressView.translatesAutoresizingMaskIntoConstraints = NO;
        
        [self addSubview:_progressView];
        
        [self addConstraint:[NSLayoutConstraint constraintWithItem:_progressView attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeWidth multiplier:1.0 constant:0]];
        [self addConstraint:[NSLayoutConstraint constraintWithItem:_progressView attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeCenterX multiplier:1.0 constant:0]];
        [self addConstraint:[NSLayoutConstraint constraintWithItem:_progressView attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeBottom multiplier:1.0 constant:0]];
        
    }
    
    return self;
}


- (void)setProgressBarColor:(UIColor *)color
{
    [self.progressView setProgressTintColor:color];
}

- (void)setProgress:(CGFloat)progress animated:(BOOL)animated;
{
    [self.progressView setProgress:(float)progress animated:animated];
}


+ (BOOL)automaticallyNotifiesObserversOfVisible
{
    return NO;
}

- (void)setProgressBarVisible:(BOOL)visible aniamted:(BOOL)animated
{
    if (_visible != visible) {
        
        self.progressView.alpha = visible ? 0.0f : 1.0f;
        [UIView animateWithDuration:animated ? 0.35f : 0.0f delay:visible ? 0.2f : 0.0f options:0 animations:^{
            self.progressView.alpha = visible ? 1.0f : 0.0f;
        } completion:nil];
        
        [self willChangeValueForKey:PropertyKey(isVisible)];
        _visible = visible;
        [self didChangeValueForKey:PropertyKey(isVisible)];
        
    }
}

@end

This is all kind of moot now that we have SFSafariViewController...