good_code.m

#import "PFObject+SubclassInit.h"

@implementation PFObject (SubclassInit)

+ (instancetype)subclass
{
    Class klass = self;
    SEL selector = @selector(parseClassName);
    if ([klass respondsToSelector:selector]) {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Warc-performSelector-leaks"
        NSString *className = [klass performSelector:selector];
#pragma clang diagnostic pop
        return [[self alloc] initWithClassName:className];
    } else {
        NSException *exc = [[NSException alloc] initWithName:NSInternalInconsistencyException
                                                      reason:@"Not a PFSubclassing class"
                                                    userInfo:nil];
        [exc raise];
        return nil;
    }
}

+ (instancetype)subclassWithoutDataWithObjectId:(NSString *)objectId
{
    Class klass = self;
    SEL selector = @selector(parseClassName);
    if ([klass respondsToSelector:selector]) {
        SEL selector = @selector(objectWithoutDataWithObjectId:);
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Warc-performSelector-leaks"
        return [klass performSelector:selector withObject:objectId];
#pragma clang diagnostic pop
    } else {
        NSException *exc = [[NSException alloc] initWithName:NSInternalInconsistencyException
                                                      reason:@"Not a PFSubclassing class"
                                                    userInfo:nil];
        [exc raise];
        return nil;
    }
}

@end