Wrapper for Objective-C runtime property functions

ClassProperty.h

@import Foundation;
@import ObjectiveC.runtime;


typedef NS_ENUM(char, SetterType) {
    Assign, Strong, Weak, Copy
};


@interface ClassProperty : NSObject

@property (nonatomic, readonly) NSString *name;

/// This will be the raw type encoding for now
@property (nonatomic, readonly) NSString *encodeType;

@property (nonatomic, readonly) BOOL isReadOnly;
@property (nonatomic, readonly) BOOL isNonAtomic;
@property (nonatomic, readonly) BOOL isDynamic;
@property (nonatomic, readonly) SetterType setterType;

/// Custom getter or the default getter
@property (nonatomic, readonly) SEL getter;

/// Custom or default setter, NULL if the property is readonly
@property (nonatomic, readonly, nullable) SEL setter;

/// Will be nil if the property is computed or dynamic
@property (nonatomic, readonly, nullable) NSString *ivarName;

- (instancetype)initWithProperty:(objc_property_t)property;

@end

ClassProperty.m

@implementation ClassProperty

@synthesize getter = _getter;
@synthesize setter = _setter;

- (instancetype)initWithProperty:(objc_property_t)property {
    self = [super init];
    if (self) {
        _name = @(property_getName(property));
        _setterType = Assign;  // this is the default
        NSString *attribStr = @(property_getAttributes(property));
        NSArray *attribs = [attribStr componentsSeparatedByString:@","];

        for (NSString *attrib in attribs) {
            unichar attribChar = [attrib characterAtIndex:0];
            NSString *attribDetail = [attrib substringFromIndex:1];

            switch (attribChar) {
                case 'T':
                    _encodeType = attribDetail;
                    break;
                case 'R':
                    _isReadOnly = YES;
                    break;
                case 'N':
                    _isNonAtomic = YES;
                    break;
                case 'D':
                    _isDynamic = YES;
                    break;
                case '&':
                    _setterType = Strong;
                    break;
                case 'W':
                    _setterType = Weak;
                    break;
                case 'C':
                    _setterType = Copy;
                    break;
                case 'G':
                    _getter = NSSelectorFromString(attribDetail);
                    break;
                case 'S':
                    _setter = NSSelectorFromString(attribDetail);
                    break;
                case 'V':
                    _ivarName = attribDetail;
                    break;
                default:
                    NSAssert(NO, @"Unknown attribute: %@", attrib);
            }
        }

        if (_getter == NULL) {
            _getter = NSSelectorFromString(_name);
        }

        if (_setter == NULL && _isReadOnly == NO) {
            NSString *name = [NSString stringWithFormat:@"set%@%@:",
                              [_name substringToIndex:1].uppercaseString,
                              [_name substringFromIndex:1]];
            _setter = NSSelectorFromString(name);
        }
    }
    return self;
}

@end

NSObject+Introspection.m

@interface NSObject (Introspection)
@property (class, readonly) NSArray<ClassProperty *> *classProperties;
@end

@implementation NSObject (Introspection)

+ (NSArray<ClassProperty *> *)classProperties {
    NSMutableArray *clsProps = [NSMutableArray array];
    uint propCount;
    objc_property_t *props = class_copyPropertyList(self.class, &propCount);
    for (uint n = 0; n < propCount; n++) {
        [clsProps addObject:[[ClassProperty alloc] initWithProperty:props[n]]];
    }
    free(props);
    return clsProps;
}

@end