[RunTime练习二]属性的遍历

分手后的思念是犯贱 2022-08-19 11:08 136阅读 0赞

#import <UIKit/UIKit.h>
    #import <Foundation/Foundation.h>
    
    @interface MyTestObj : UIButton
    
    @property (nonatomic,retain) NSNumber* MyNumber;
    @property (nonatomic) NSInteger MyInteger;
    @property (nonatomic, readwrite, copy) NSString* MyString;
    @property (nonatomic,retain)NSMutableArray* MyArray;
    @property (nonatomic,retain)NSMutableDictionary* MyDictionary;
    @end

#import "MyTestObj.h"
    
    @implementation MyTestObj
    
    -(instancetype) init
    {
        if (self = [super init]) {
            self.MyArray = [[NSMutableArray alloc] initWithObjects:@"hello", nil];
            self.MyDictionary = [[NSMutableDictionary alloc]initWithCapacity:1];
            [self.MyDictionary setObject:@"hello" forKey:@"world"];
            self.MyString = @"hello world";
            self.MyNumber = [NSNumber numberWithInteger:100];
            self.MyInteger = 80;
        }
        return  self;
    }
    @end

#import "ViewController.h"
    #import "MyTestObj.h"
    #import <objc/runtime.h>
    
    @interface ViewController ()
    
    @end
    
    @implementation ViewController
    
    - (void)viewDidLoad {
        [super viewDidLoad];
        MyTestObj* M = [[MyTestObj alloc] init];
        NSInvocation* invoc ;
        unsigned PropertiesCount = 0;
        objc_property_t* properties = class_copyPropertyList([M class], &PropertiesCount);
        for (int i = 0; i < PropertiesCount; i++) {
            @autoreleasepool {
                objc_property_t prop = properties[i];
                NSString* propName = [NSMutableString stringWithFormat:@"%s",property_getName(prop)];
                SEL s = NSSelectorFromString(propName);
                //sign和invoc都只能通过类方法得到(可能有别的，我不太清楚～)，写在for循环里面浪费了～～
                NSMethodSignature* sign = [[M class] instanceMethodSignatureForSelector:s];
                invoc = [NSInvocation invocationWithMethodSignature:sign];
                [invoc setSelector:s];
                [invoc setTarget:M];
                [invoc invoke];
                if (strcmp([sign methodReturnType], @encode(void)) == 0) {
                    NSLog(@"Return None~");
                }
                else if (strcmp([sign methodReturnType], @encode(NSInteger)) == 0)
                {
                    void* pValue = (void*)malloc([sign methodReturnLength]);
                    [invoc getReturnValue:pValue];
                    id result = [NSNumber numberWithInteger:*((NSInteger*)pValue)];
                    NSLog(@"Ruturn NSInteger %@",result);
                }
                else
                {
                    void* pValue = (void*)malloc([sign methodReturnLength]);
                    [invoc getReturnValue:&pValue];
                    id result = (__bridge id)pValue;
                    NSLog(@"Return object %@",result);
                }
    
            }
        }
        // Do any additional setup after loading the view, typically from a nib.
    }
    
    - (void)didReceiveMemoryWarning {
        [super didReceiveMemoryWarning];
        // Dispose of any resources that can be recreated.
    }

1，可以遍历对象对应类的某一层次的所有属性（只写属性没考虑～）。

2，instanceMethodSignatureForSelector，不仅能获取方法的签名，也能获取属性的签名，再次印证了，@property声明的属性，读取方法就是属性名。

3，nsinvocation在调用的时候，即使是返回值，也会release,所以如果不申请内存，来放返回值，那么oc对象的引用计数就混乱了。retainArguments只retain了参数。

**上面的这些操作完全是为了巩固下nsinvocation的用法，获取属性值，完全可以用［M ValueForKey:propName］来完成～～**

参考：http://www.cnblogs.com/pengyingh/articles/2359199.html