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控制器属性传值的一些小问题
控制器属性传值的一些小问题
这篇博文并没有什么技术含量，属于很基础的知识，但也容易在感官上产生错误的认识，今天记录于此。
一个对象，无论是被转存到数组中，还是被多个控制器持有，如果这个对象没有发生值的拷贝（创建出新的对象），所有的对这个对象的持有者只持有了一个样本，修改了这个样本的值会影响到所有持有者。
效果演示图：
测试用源码：
DataModel.h 与 DataModel.m
//// DataModel.h// BaseViewController//// Created by YouXianMing on 15/1/2.// Copyright (c) 2015年 YouXianMing. All rights reserved.//#import <Foundation/Foundation.h>@interface DataModel : NSObject@property (nonatomic, strong) NSString *name;@property (nonatomic, strong) NSNumber *age;@property (nonatomic, strong) NSArray *array;@end
//// DataModel.m// BaseViewController//// Created by YouXianMing on 15/1/2.// Copyright (c) 2015年 YouXianMing. All rights reserved.//#import "DataModel.h"@implementation DataModel@end
ChangeValueViewController.h 与 ChangeValueViewController.m
//// ChangeValueViewController.h// BaseViewController//// Created by YouXianMing on 15/1/2.// Copyright (c) 2015年 YouXianMing. All rights reserved.//#import <UIKit/UIKit.h>#import "DataModel.h"@interface ChangeValueViewController : UIViewController@property (nonatomic, strong) DataModel *dataModel;@end
//// ChangeValueViewController.m// BaseViewController//// Created by YouXianMing on 15/1/2.// Copyright (c) 2015年 YouXianMing. All rights reserved.//#import "ChangeValueViewController.h"@interface ChangeValueViewController ()@property (nonatomic, strong) UILabel *label;@end@implementation ChangeValueViewController- (void)viewDidLoad { [super viewDidLoad]; self.view.backgroundColor = [UIColor yellowColor]; self.dataModel.age = @(self.dataModel.age.intValue + 1); self.dataModel.array = @[@"2", @"1", @"2"]; [self createButton]; [self createLabel];}#pragma mark - 创建出label- (void)createLabel { self.label = [[UILabel alloc] initWithFrame:self.view.bounds]; self.label.text = @"Back"; self.label.font = [UIFont fontWithName:@"HelveticaNeue-Thin" size:70.f]; self.label.textAlignment = NSTextAlignmentCenter; self.label.textColor = [UIColor grayColor]; [self.view addSubview:self.label];}#pragma mark - 创建按钮以及按钮事件- (void)createButton { UIButton *button = [[UIButton alloc] initWithFrame:self.view.bounds]; [self.view addSubview:button]; [button addTarget:self action:@selector(buttonEvent:) forControlEvents:UIControlEventTouchUpInside];}- (void)buttonEvent:(UIButton *)button { [self dismissViewControllerAnimated:YES completion:^{ }];}@end
ViewController.m
//// ViewController.m// BaseViewController//// Created by YouXianMing on 15/1/2.// Copyright (c) 2015年 YouXianMing. All rights reserved.//#import "ViewController.h"#import "ChangeValueViewController.h"#import "DataModel.h"@interface ViewController ()@property (nonatomic, strong) DataModel *dataModel; // 数据model@property (nonatomic, strong) UILabel *label;@end@implementation ViewController- (void)viewDidLoad { [super viewDidLoad]; // 数据model self.dataModel = [DataModel new]; self.dataModel.name = @"YouXianMing"; self.dataModel.age = @(27); self.dataModel.array = @[@"1"]; [self createButton]; [self createLabel];}#pragma mark - 创建出label- (void)createLabel { self.label = [[UILabel alloc] initWithFrame:self.view.bounds]; self.label.text = [NSString stringWithFormat:@"%@ - %@", self.dataModel.name, self.dataModel.age]; self.label.font = [UIFont fontWithName:@"HelveticaNeue-Thin" size:30.f]; self.label.textAlignment = NSTextAlignmentCenter; self.label.textColor = [UIColor grayColor]; [self.view addSubview:self.label];}#pragma mark - 创建按钮以及按钮事件- (void)createButton { UIButton *button = [[UIButton alloc] initWithFrame:self.view.bounds]; [self.view addSubview:button]; [button addTarget:self action:@selector(buttonEvent:) forControlEvents:UIControlEventTouchUpInside];}- (void)buttonEvent:(UIButton *)button { ChangeValueViewController *changeValueViewCV = [ChangeValueViewController new]; // 获取数据 changeValueViewCV.dataModel = self.dataModel; [self presentViewController:changeValueViewCV animated:YES completion:^{ }];}#pragma mark - 控制器view- (void)viewWillAppear:(BOOL)animated { self.label.text = [NSString stringWithFormat:@"%@-%@", self.dataModel.name, self.dataModel.age]; NSLog(@"%@", self.dataModel.array);}@end
只要DataModel被ViewController一直持有，所有的持有这个DataModel的控制器，修改了DataModel的值，就会影响到全局的值，这点需要注意哦。
控制器属性传值的一些小问题
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