setting new properties in category interface/implementation

Question

Ok, so I have this, but it wont work:

@interface UILabel (touches)

@property (nonatomic) BOOL isMethodStep;

@end


@implementation UILabel (touches)

-(BOO         


        

Answer 1

It is not possible to add members and properties to an existing class via a category — only methods.

https://developer.apple.com/library/content/documentation/General/Conceptual/DevPedia-CocoaCore/Category.html

One possible workaround is to write "setter/getter-like" methods, that uses a singleton to save the variables, that would had been the member.

-(void)setMember:(MyObject *)someObject
{
    NSMutableDictionary *dict = [MySingleton sharedRegistry];
    [dict setObject:someObject forKey:self];
}

-(MyObject *)member
{
    NSMutableDictionary *dict = [MySingleton sharedRegistry];
    return [dict objectforKey:self];
}

or — of course — write a custom class, that inherits from UILabel

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Note that nowadays an associated object can be injected during runtime. The Objective C Programming Language: Associative References