iOS OC readOnly 和属性 详解

//
//  ViewController.h
//  test_category_01
//
//  Created by admin on 4/20/16.
//  Copyright © 2016 jeffasd. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController
{
    NSUInteger _viewInsetTop;
}

@property (assign, nonatomic, readonly)NSUInteger viewInsetTop;

@end

//
//  ViewController.m
//  test_category_01
//
//  Created by admin on 4/20/16.
//  Copyright © 2016 jeffasd. All rights reserved.
//

#import "ViewController.h"
#import "UIView+Jeffasd.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    self.view.viewName = @"sdfsdf";
    
    NSLog(@"the viewName is %@", self.view.viewName);
    
    _viewInsetTop = 122;
    
    NSLog(@"the top is %lu", (unsigned long)self.viewInsetTop);
    
}

//- (NSUInteger)viewInsetTop{
//    return _viewInsetTop;
//}
//
//- (void)setViewInsetTop:(NSUInteger)viewInsetTop{
//    _viewInsetTop = viewInsetTop;
//}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

//注意这里的self.viewInsetTop打印出的值就是_viewInsetTop的值，从其set和get方法就能判断出来