NSObject+AssociatedObjects.h

//
//  NSObject+NSObject_AssociatedObjects.h
//  Created by Kristian Trenskow.
//
 
#import <Foundation/Foundation.h>
 
/**
 Associated objects additions to `NSObject`.
 */
@interface NSObject (AssociatedObjects)
 
/**
 Returns an `NSMutableDictionary` instance with associated objects.
 */
@property (nonatomic,readonly,nonnull) NSMutableDictionary<NSString *, id> *associatedObjects;
 
@end

NSObject+AssociatedObjects.m

//
//  NSObject+AssociatedObjects.m
//  Created by Kristian Trenskow.
//
 
#import <objc/runtime.h>
 
#import "NSObject+AssociatedObjects.h"
 
unsigned int NSObjectAssociatedObjectsKey = 0;
 
@implementation NSObject (AssociatedObjects)
 
- (NSMutableDictionary<NSString *,id> *)associatedObjects {
     
    // If no associated object has been set - we create one, set it and return it.
     
    NSMutableDictionary<NSString *, id> *associatedObjects = objc_getAssociatedObject(self, &NSObjectAssociatedObjectsKey);
    if (!associatedObjects) {
        associatedObjects = [NSMutableDictionary new];
        objc_setAssociatedObject(self, &NSObjectAssociatedObjectsKey, associatedObjects, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    }
    return associatedObjects;
     
}
 
@end

NSObject+Properties.h

//
//  NSObject+Properties.h
//  Created by Kristian Trenskow.
//
 
#import <Foundation/Foundation.h>
 
/**
 A class representing runtime information a property.
 */
@interface NSPropertyInfo : NSObject
 
/**
 Returns the properties name.
 */
@property (nonatomic,readonly,nonnull) NSString *name;
/**
 Returns `YES` if property is read-only.
 */
@property (nonatomic,readonly,getter=isReadOnly) BOOL readOnly;
/**
 Returns `YES` if property's value is copied on set.
 */
@property (nonatomic,readonly,getter=isCopy) BOOL copy;
/**
 Returns `YES` if property's value is holds a strong reference.
 */
@property (nonatomic,readonly,getter=isStrong) BOOL strong;
/**
 Returns `YES` if property is atomic.
 */
@property (nonatomic,readonly,getter=isAtomic) BOOL atomic;
/**
 Returns the selector for the getter.
 */
@property (nonatomic,readonly,nonnull) SEL getter;
/**
 Returns the selector for the setter.
 */
@property (nonatomic,readonly,nonnull) SEL setter;
/**
 Returns `YES` if the property's implementation is dynamic - added at runtime.
 */
@property (nonatomic,readonly,getter=isDynamic) BOOL dynamic;
/**
 Returns `YES` if the property holds a weak reference.
 */
@property (nonatomic,readonly,getter=isWeak) BOOL weak;
/**
 Return `YES` if the property can be garbage collected (Mac OS X only).
 */
@property (nonatomic,readonly,getter=isGarbageCollectable) BOOL garbageCollectable;
/**
 Returns the type encoding for the property.
 */
@property (nonatomic,readonly,nonnull) NSString *typeEncoding;
/**
 When `typeEncoding` is `@` it returns the `Class` of the property - otherwise nil.
 @note This is only non-nil if the information is available at runtime.
 */
@property (nonatomic,readonly,nullable) Class type;
 
@end
 
/**
 Properties additions to `NSObject`.
 */
@interface NSObject (Properties)
 
/**
 Returns an `NSDictionary` instance where the key is the property name and the value is an `NSPropertyInfo` object with property information.
 */
@property (nonatomic,readonly,nonnull) NSDictionary<NSString *, NSPropertyInfo *> *properties;
 
@end

NSObject+Properties.m

//
//  NSObject+Properties.m
//  Created by Kristian Trenskow.
//
 
#import <objc/runtime.h>
 
#import "NSObject+AssociatedObjects.h"
 
#import "NSObject+Properties.h"
 
@interface NSPropertyInfo ()
 
@property (nonatomic,readwrite,nonnull) NSString *name;
@property (nonatomic,readwrite,getter=isReadOnly) BOOL readOnly;
@property (nonatomic,readwrite,getter=isCopy) BOOL copy;
@property (nonatomic,readwrite,getter=isStrong) BOOL strong;
@property (nonatomic,readwrite,getter=isAtomic) BOOL atomic;
@property (nonatomic,readwrite,nonnull) SEL getter;
@property (nonatomic,readwrite,nonnull) SEL setter;
@property (nonatomic,readwrite,getter=isDynamic) BOOL dynamic;
@property (nonatomic,readwrite,getter=isWeak) BOOL weak;
@property (nonatomic,readwrite,getter=isGarbageCollectable) BOOL garbageCollectable;
@property (nonatomic,readwrite,nonnull) NSString *typeEncoding;
@property (nonatomic,readwrite,nullable) Class type;
 
@end
 
NSString * const NSPropertiesKey = @"NSPropertiesKey";

@implementation NSPropertyInfo
 
- (instancetype)initWithProperty:(objc_property_t)property {
     
    if ((self = [super init])) {
        _name = [NSString stringWithCString:property_getName(property) encoding:NSUTF8StringEncoding];
         
        // ARC default property attributes.
        _strong = YES;
        _atomic = YES;
        _getter = NSSelectorFromString(_name);
        _setter = NSSelectorFromString([NSString stringWithFormat:@"set%@%@",
                                        [[_name substringWithRange:NSMakeRange(0, 1)] uppercaseString],
                                        [_name substringFromIndex:1]]);
         
        NSArray<NSString *> *attributes = [[NSString stringWithCString:property_getAttributes(property)
                                                              encoding:NSUTF8StringEncoding]
                                           componentsSeparatedByString:@","];
         
        for (NSString *attribute in attributes) {
            switch ([attribute characterAtIndex:0]) {
                case 'R':
                    _readOnly = YES;
                    break;
                case 'C':
                    _copy = YES;
                    break;
                case '&':
                    _strong = YES;
                    break;
                case 'N':
                    _atomic = NO;
                    break;
                case 'G':
                    _getter = NSSelectorFromString([attribute substringFromIndex:1]);
                    break;
                case 'S':
                    _setter = NSSelectorFromString([attribute substringFromIndex:1]);
                    break;
                case 'D':
                    _dynamic = YES;
                    break;
                case 'W':
                    _weak = YES;
                    break;
                case 'P':
                    _garbageCollectable = YES;
                    break;
                case 'T':
                    _typeEncoding = [attribute substringFromIndex:1];
                    if ([_typeEncoding characterAtIndex:0] == '@' && [_typeEncoding length] > 1) {
                        _type = NSClassFromString([_typeEncoding substringWithRange:NSMakeRange(2, [_typeEncoding length] - 3)]);
                        _typeEncoding = @"@";
                    }
                    break;
            }
        }
    }
     
    return self;
     
}
 
@end
 
@implementation NSObject (Properties)
 
- (NSDictionary<NSString *,NSObjectPropertyInfo *> *)properties {
     
    NSDictionary<NSString *, NSObjectPropertyInfo *> *ret = self.associatedObjects[NSObjectPropertiesKey];
     
    if (!ret) {
         
        NSMutableDictionary<NSString *, NSObjectPropertyInfo *> *infos = [NSMutableDictionary new];
         
        Class currentClass = [self class];
        while (currentClass != [NSObject class]) {
            unsigned int count;
            objc_property_t *properties = class_copyPropertyList(currentClass, &count);
            for (unsigned int idx = 0 ; idx < count ; idx++) {
                NSObjectPropertyInfo *propertyInfo = [[NSObjectPropertyInfo alloc] initWithProperty:properties[idx]];
                infos[propertyInfo.name] = propertyInfo;
            }
            currentClass = [currentClass superclass];
            free(properties);
        }
         
        ret = self.associatedObjects[NSObjectPropertiesKey] = [infos copy];
         
    }
     
    return ret;
     
}
 
@end

I know it's really a "no no!" to name things in the NS namespace - but this is just an example - so just rename if you don't like it.