NSString+URLValidation.h

#import <Foundation/Foundation.h>

@interface NSString (URLValidation)
- (BOOL)isValidURL;
@end

NSString+URLValidation.m

#import "NSString+URLValidation.h"

@implementation NSString (URLValidation)

- (BOOL)isValidURL
{
    NSUInteger length = [self length];
    // Empty strings should return NO
    if (length > 0) {
        NSError *error = nil;
        NSDataDetector *dataDetector = [NSDataDetector dataDetectorWithTypes:NSTextCheckingTypeLink error:&error];
        if (dataDetector && !error) {
            NSRange range = NSMakeRange(0, length);
            NSRange notFoundRange = (NSRange){NSNotFound, 0};
            NSRange linkRange = [dataDetector rangeOfFirstMatchInString:self options:0 range:range];
            if (!NSEqualRanges(notFoundRange, linkRange) && NSEqualRanges(range, linkRange)) {
                return YES;
            }
        }
        else {
            NSLog(@"Could not create link data detector: %@ %@", [error localizedDescription], [error userInfo]);
        }
    }
    
    return NO;
}

@end

NSString+URLValidationTests.m

#import <UIKit/UIKit.h>
#import <XCTest/XCTest.h>
#import "NSString+URLValidation.h"

@interface NSString_URLValidationTests : XCTestCase

@end

@implementation NSString_URLValidationTests

- (void)setUp {
    [super setUp];
    // Put setup code here. This method is called before the invocation of each test method in the class.
}

- (void)tearDown {
    // Put teardown code here. This method is called after the invocation of each test method in the class.
    [super tearDown];
}

//////////////////////////////////////////////////////////////////////////////
#pragma mark ---- Validation Tests
//////////////////////////////////////////////////////////////////////////////

- (void)testIsValidURL {
    // wrong formats
    NSString* testString = nil;
    XCTAssertFalse([testString isValidURL], @"'nil' string is not a valid URL");
    testString = @"";
    XCTAssertFalse([testString isValidURL], @"'empty' string is not a valid URL");
    testString = @"about:blank";
    XCTAssertFalse([testString isValidURL], @"'about:page' string is not a valid URL");
    
    // correct formats
    testString = @"http://example.com";
    XCTAssertTrue([testString isValidURL]);
    testString = @"https://example.com";
    XCTAssertTrue([testString isValidURL]);
    testString = @"https://igcdn-photos-d-a.akamaihd.net/hphotos-ak-xaf1/t51.2885-15/11049325_454620968038899_1613081310_n.jpg";
    XCTAssertTrue([testString isValidURL]);
}

@end