豆瓣收藏的功能封装

1.判断活动是否收藏过(使用时最号用一个属性保存返回值,方便之后操作)

// 判断活动是否收藏过+ (BOOL)isActivityInPlist:(Activity *)activity;

1.先将文件反归档  2.之后判断数组是否是空,如果是空返回NO  3.之后遍历数组,判断是否有元素,如果有返回YES,没有返回NO

+ (BOOL)isActivityInPlist:(Activity *)activity{    NSString *sandBoxPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, 1, YES) lastObject];    NSString *docPath = [sandBoxPath stringByAppendingPathComponent:@"activity.plist"];    // 反归档,判断是否收藏    NSArray *actArr = [NSKeyedUnarchiver unarchiveObjectWithFile:docPath];    if (actArr == nil) {        return NO;    } else {        for (Activity *temp in actArr) {            if ([temp.activityId isEqualToString:activity.activityId]) {                return YES;            }        }        return NO;    }}

 self.isSave = [SaveTool isActivityInPlist:self.activity];          // 根据收藏的状态改变button按钮    if (self.isSave) {        [button setTitle:@"已收藏" forState:UIControlStateNormal];    } else {        [button setTitle:@"收藏" forState:UIControlStateNormal];    }        self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:button];    self.title = self.activity.title;    NSLog(@"%@", self.activity.activityId);

2.归档:为了防止原来的数据被覆盖掉,所以一般先把数据进行反归档,把数据读出来之后,新数据加进去,在进行归档

两种情况:1.数组为空的时候,需要初始化数组 2.在读出来的数组中增加元素,归档

+ (void)saveActivityInPlist:(Activity *)activity{    // 为了防止原来的数据被覆盖掉,所以一般先把数据进行反归档,把数据读出来之后,新数据加进去,在进行归档    NSString *sandBoxPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, 1, YES) lastObject];    NSString *docPath = [sandBoxPath stringByAppendingPathComponent:@"activity.plist"];        NSMutableArray *arr = [NSKeyedUnarchiver unarchiveObjectWithFile:docPath];    // 有两种情况,第一种,数组为空,需要初始化一个数组    if (arr == nil) {        arr = [NSMutableArray array];    }    // 如果加了else,空数组就不会添加元素    [arr addObject:activity];    // 归档    [NSKeyedArchiver archiveRootObject:arr toFile:docPath];}

封装一个函数,实现收藏和取消收藏的功能(需要在函数中传一个状态,判断是收藏还是取消收藏的功能)

1.如果状态是NO,归档收藏   2.如果不是,取消收藏.需要遍历找到元素,然后删除,之后归档

+ (void)saveActivityOrCancel:(Activity *)activity state:(BOOL)state{    // 根据传过来的布尔判断当前的操作    if (state == NO) {        // 归档收藏        [SaveTool saveActivityInPlist:activity];    } else {        // 删除,取消收藏        // 删除        NSString *sandBoxPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, 1, YES) lastObject];        NSString *docPath = [sandBoxPath stringByAppendingPathComponent:@"activity.plist"];        // 反归档        NSMutableArray *arr = [NSKeyedUnarchiver unarchiveObjectWithFile:docPath];        // 不需要判断        // 遍历找到元素,不遍历找不到元素        for (Activity *temp in arr) {            if ([temp.activityId isEqualToString:activity.activityId]) {                [arr removeObject:temp];                break;            }        }        [NSKeyedArchiver archiveRootObject:arr toFile:docPath];    }}

 [SaveTool saveActivityOrCancel:self.activity state:self.isSave];    if (self.isSave) {        [button setTitle:@"收藏" forState:UIControlStateNormal];    } else {        [button setTitle:@"已收藏" forState:UIControlStateNormal];    }    // 最后对状态进行取反    self.isSave = !self.isSave;

查找收藏详情(返回一个数组,不需要传参数)

+ (NSMutableArray *)searchAcitivityInPlist{     NSString *sandBoxPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, 1, YES) lastObject];     NSString *docPath = [sandBoxPath stringByAppendingPathComponent:@"activity.plist"];     NSMutableArray *arr = [NSKeyedUnarchiver unarchiveObjectWithFile:docPath];    return arr;}

因为需要刷新数据,对数据进行实时的更新,所以要把方法写在viewWillAppear里

// 重写这个方法,完成实时的更新数据- (void)viewWillAppear:(BOOL)animated{    [super viewWillAppear:animated];    // 这个要再这里写,cell是最后执行的函数    self.arr = [SaveTool searchAcitivityInPlist];    [self.tableView reloadData];}