Loop through all object properties at runtime

Question

I want to create an Objective-C base class that performs an operation on all properties (of varying types) at runtime. Since the names and types of the properties will not a

Answer 1

Adding some detial to @mvds:

unsigned int count=0;
objc_property_t *props = class_copyPropertyList([self class],&count);
for ( int i=0;i<count;i++ )
{
    const char *name = property_getName(props[i]);
    NSString* dataToGet = [NSString swf:@"%s",name];
    @try { // in case of this pair not key value coding-compliant
        id value = [barButton valueForKey:dataToGet];
        NSLog(@"prop %d: %s  %@",i,name, value);
    } @catch (NSException *exception) {
        // NSLog(@"Exception:%@",exception);
    }
    @finally {
        // Display Alternative
    }
}

Please give @mvds the upvote.

Answer 2

Use

objc_property_t * class_copyPropertyList(Class cls, unsigned int *outCount)

and read https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/ObjCRuntimeRef/Reference/reference.html on how to do this exactly.

Some code to get you going:

#import <objc/runtime.h>

unsigned int count=0;
objc_property_t *props = class_copyPropertyList([self class],&count);
for ( int i=0;i<count;i++ )
{
    const char *name = property_getName(props[i]); 
    NSLog(@"property %d: %s",i,name);
}

Answer 3

To expand on mvds' answer (started writing this before I saw his), here's a little sample program that uses the Objective-C runtime API to loop through and print information about each property in a class:

#import <Foundation/Foundation.h>
#import <objc/runtime.h>

@interface TestClass : NSObject

@property (nonatomic, retain) NSString *firstName;
@property (nonatomic, retain) NSString *lastName;
@property (nonatomic) NSInteger *age;

@end

@implementation TestClass

@synthesize firstName;
@synthesize lastName;
@synthesize age;

@end

int main(int argc, char *argv[]) {
    @autoreleasepool {
        unsigned int numberOfProperties = 0;
        objc_property_t *propertyArray = class_copyPropertyList([TestClass class], &numberOfProperties);

        for (NSUInteger i = 0; i < numberOfProperties; i++)
        {
            objc_property_t property = propertyArray[i];
            NSString *name = [[NSString alloc] initWithUTF8String:property_getName(property)];
            NSString *attributesString = [[NSString alloc] initWithUTF8String:property_getAttributes(property)];
            NSLog(@"Property %@ attributes: %@", name, attributesString);
        }
        free(propertyArray);
    }
}

Output:

Property age attributes: T^q,Vage
Property lastName attributes: T@"NSString",&,N,VlastName
Property firstName attributes: T@"NSString",&,N,VfirstName

Note that this program needs to be compiled with ARC turned on.