Remove default Mac Catalyst application text field focus rings

UITextField+CTX.h

//
//  UITextField+CTX.h
//  EFClass
//
//  Created by Stefan Ceriu on 27/11/2019.
//  Copyright © 2019 EF Education First. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface UITextField (CTX)

@end

UITextField+CTX.m

//
//  UITextField+CTX.m
//  EFClass
//
//  Created by Stefan Ceriu on 27/11/2019.
//  Copyright © 2019 EF Education First. All rights reserved.
//

#import "UITextField+CTX.h"

#import <objc/runtime.h>

@implementation UITextField (CTX)

+ (void)load
{
#if TARGET_OS_MACCATALYST
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        CTXSwizzleInstanceMethod([self class], NSSelectorFromString(@"_focusRingType"), @selector(ctx_focusRingType));
    });
#endif
}

- (NSUInteger)ctx_focusRingType
{
    return 1; // NSFocusRingTypeNone
}

static void CTXSwizzleInstanceMethod(Class class, SEL originalSelector, SEL swizzledSelector) {
    Method originalMethod = class_getInstanceMethod(class, originalSelector);
    Method swizzledMethod = class_getInstanceMethod(class, swizzledSelector);
    
    if (class_addMethod(class, originalSelector, method_getImplementation(swizzledMethod), method_getTypeEncoding(swizzledMethod))) {
        class_replaceMethod(class, swizzledSelector, method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod));
    } else {
        method_exchangeImplementations(originalMethod, swizzledMethod);
    }
}

@end