类目添加变量

#import <UIKit/UIKit.h>
#include <objc/runtime.h>
#include <objc/objc-runtime.h>

@interface UIView (DHStyleManager)


@property(nonatomic,copy)NSString *styleName;
@end

static char KDHStyleKey;

#import "UIView+DHStyleManager.h"

@implementation UIView (DHStyleManager)
@dynamic styleName;

-(void)setStyleName:(NSString *)aStyleName
{
    objc_setAssociatedObject(self,&KDHStyleKey,aStyleName,OBJC_ASSOCIATION_COPY);
}

-(NSString *)styleName
{
    return objc_getAssociatedObject(self, &KDHStyleKey);
}

@end

UIView *v = [[UIView alloc]init];
    v.styleName = @"someStyleName";
    NSLog(@"v = %@",v.styleName);