Dispatch after

Objc version

#import <Foundation/Foundation.h>

// Bool
@interface BoolNum:NSObject
@property(nonatomic) BOOL isCancel;
@end

@implementation BoolNum
@end


/// Solution
@interface Solution:NSObject
+ (BoolNum*)dispatchAfterWithCancel:(NSInteger)delayTime block:(void(^)())block;
@end

@implementationSolution
+ (BoolNum*)dispatchAfterWithCancel:(NSInteger)delayTime block:(void(^)())block {
    BoolNum* obj = [[BoolNum alloc] init];
    obj.isCancel = NO;
    void(^myBlock)() = ^{
        if(obj.isCancel == NO) {
            block();
        }
    };

    dispatch_after(
        dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayTime *NSEC_PER_SEC)), 
        dispatch_get_global_queue(0,0), 
        ^{
            myBlock();
    });

    return obj;
}
@end

int main(intargc,constchar* argv[]) {
    @autoreleasepool{
        // insert code here...
        NSLog(@"Hello, World!");
        BoolNum* obj = [Solution dispatchAfterWithCancel:2 block:^{
            NSLog(@"xxx");
        }];
        obj.isCancel =YES;
        sleep(3);
    }
    return0;
}

Swift version