react-native-navigation/lib/ios/RNNUIBarButtonItem.m

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
#import "RNNUIBarButtonItem.h"
#import "RCTConvert+UIBarButtonSystemItem.h"

@interface RNNUIBarButtonItem ()

@property (nonatomic, strong) NSLayoutConstraint *widthConstraint;
@property (nonatomic, strong) NSLayoutConstraint *heightConstraint;

@end

@implementation RNNUIBarButtonItem

-(instancetype)init:(NSString*)buttonId withIcon:(UIImage*)iconImage {
	UIButton* button = [[UIButton alloc] init];
	[button addTarget:self action:@selector(onButtonPressed) forControlEvents:UIControlEventTouchUpInside];
	[button setImage:iconImage forState:UIControlStateNormal];
	[button setFrame:CGRectMake(0, 0, iconImage.size.width, iconImage.size.height)];
	self = [super initWithCustomView:button];
	self.buttonId = buttonId;
	return self;
}

-(instancetype)init:(NSString*)buttonId withTitle:(NSString*)title {
	self = [super initWithTitle:title style:UIBarButtonItemStylePlain target:nil action:nil];
	self.buttonId = buttonId;
	return self;
}

-(instancetype)init:(NSString*)buttonId withCustomView:(RCTRootView *)reactView {
	self = [super initWithCustomView:reactView];
	
	reactView.sizeFlexibility = RCTRootViewSizeFlexibilityWidthAndHeight;
	reactView.delegate = self;
	reactView.backgroundColor = [UIColor clearColor];
    reactView.hidden = CGRectEqualToRect(reactView.frame, CGRectZero);
    
	[NSLayoutConstraint deactivateConstraints:reactView.constraints];
	self.widthConstraint = [NSLayoutConstraint constraintWithItem:reactView
														attribute:NSLayoutAttributeWidth
														relatedBy:NSLayoutRelationEqual
														   toItem:nil
														attribute:NSLayoutAttributeNotAnAttribute
													   multiplier:1.0
														 constant:reactView.intrinsicContentSize.width];
	self.heightConstraint = [NSLayoutConstraint constraintWithItem:reactView
														 attribute:NSLayoutAttributeHeight
														 relatedBy:NSLayoutRelationEqual
														   	toItem:nil
														 attribute:NSLayoutAttributeNotAnAttribute
													   	multiplier:1.0
														  constant:reactView.intrinsicContentSize.height];
	[NSLayoutConstraint activateConstraints:@[self.widthConstraint, self.heightConstraint]];
	self.buttonId = buttonId;
	return self;
}
	
- (instancetype)init:(NSString*)buttonId withSystemItem:(NSString *)systemItemName {
	UIBarButtonSystemItem systemItem = [RCTConvert UIBarButtonSystemItem:systemItemName];
	self = [super initWithBarButtonSystemItem:systemItem target:nil action:nil];
	self.buttonId = buttonId;
	return self;
}

- (void)rootViewDidChangeIntrinsicSize:(RCTRootView *)rootView {
	self.widthConstraint.constant = rootView.intrinsicContentSize.width;
	self.heightConstraint.constant = rootView.intrinsicContentSize.height;
	[rootView setNeedsUpdateConstraints];
	[rootView updateConstraintsIfNeeded];
    rootView.hidden = NO;
}

- (void)onButtonPressed {
	[self.target performSelector:self.action
					  withObject:self
					  afterDelay:0];
}

@end