ios開發--KVO淺析，ios--kvo淺析

ios開發--KVO淺析，ios--kvo淺析

目標：監聽NSMutableArray對象中增加了什麼

 

代碼如下：

C代碼  

- (void)viewDidLoad  

{  

    [super viewDidLoad];  

  

    self.dataArray = [NSMutableArray arrayWithObject:@"1"];  

    [self addObserver:self forKeyPath:@"dataArray" options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld context:NULL];  

       

}  

- (void)viewDidLoad{    [super viewDidLoad];    self.dataArray = [NSMutableArray arrayWithObject:@"1"];    [self addObserver:self forKeyPath:@"dataArray" options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld context:NULL];     }

 

C代碼  

- (void) observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context  

{  

    NSLog(@"%@", keyPath);  

    NSLog(@"%@", object);  

    NSLog(@"%@", change);  

}  

- (void) observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context{    NSLog(@"%@", keyPath);    NSLog(@"%@", object);    NSLog(@"%@", change);}

 

C代碼  

- (IBAction)add:(id)sender  

{  

    NSArray *addData = [NSArray arrayWithObjects:@"11", @"12", @"13", nil];  

    [self.dataArray addObjectsFromArray:addData];  

      

    self.dataArray = [NSMutableArray arrayWithObject:@"2"];  

}  

- (IBAction)add:(id)sender{    NSArray *addData = [NSArray arrayWithObjects:@"11", @"12", @"13", nil];    [self.dataArray addObjectsFromArray:addData];        self.dataArray = [NSMutableArray arrayWithObject:@"2"];}

 

輸入日誌：

C代碼  

2013-01-15 16:05:10.120 KVOTest[2199:907] dataArray  

2013-01-15 16:05:10.121 KVOTest[2199:907] <ZZTViewController: 0x20846590>  

2013-01-15 16:05:10.123 KVOTest[2199:907] {  

    kind = 1;  

    new =     (  

        2  

    );  

    old =     (  

        1,  

        11,  

        12,  

        13  

    );  

}  

2013-01-15 16:05:10.120 KVOTest[2199:907] dataArray2013-01-15 16:05:10.121 KVOTest[2199:907] <ZZTViewController: 0x20846590>2013-01-15 16:05:10.123 KVOTest[2199:907] {    kind = 1;    new =     (        2    );    old =     (        1,        11,        12,        13    );}

 

 

經過測試得如下結論：kvo監聽的是對象指標的變動，NSString、int、float等對象的變動(abc = @"123"、abc = 12、abc = 12.2)皆為指標的變動，所以通過此方式來捕捉array的變化是不可行的

 

但，我們可以通過此方式來做控制項屬性的變動。如下：

C代碼  

- (void)viewDidLoad  

{  

    [super viewDidLoad];  

      

    self.personObject = [PersonObject personObjectWithBankInstance:[BankObject bankObjectWithAccountBalance:10]];  

      

    [self.personObject addObserver:self forKeyPath:@"bankInstance.accountBalance" options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld context:NULL];    // 此處注意是監聽personObject對象下的bankInstance的accountBalance變化  

}  

- (void)viewDidLoad{    [super viewDidLoad];        self.personObject = [PersonObject personObjectWithBankInstance:[BankObject bankObjectWithAccountBalance:10]];        [self.personObject addObserver:self forKeyPath:@"bankInstance.accountBalance" options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld context:NULL];    // 此處注意是監聽personObject對象下的bankInstance的accountBalance變化}

 

C代碼  

- (void) observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context  

{  

    NSLog(@"%@", keyPath);  

    NSLog(@"%@", object);  

    NSLog(@"%@", change);  

}  

- (void) observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context{    NSLog(@"%@", keyPath);    NSLog(@"%@", object);    NSLog(@"%@", change);}

 

C代碼  

- (IBAction)add:(id)sender  

{  

    [self.personObject.bankInstance setAccountBalance:2111];  

}  

- (IBAction)add:(id)sender{    [self.personObject.bankInstance setAccountBalance:2111];}

 輸出日誌：

C代碼  

2013-01-15 16:05:10.111 KVOTest[2199:907] bankInstance.accountBalance  

2013-01-15 16:05:10.116 KVOTest[2199:907] <PersonObject: 0x20856180>  

2013-01-15 16:05:10.118 KVOTest[2199:907] {  

    kind = 1;  

    new = 2111;  

    old = 10;  

}  

2013-01-15 16:05:10.111 KVOTest[2199:907] bankInstance.accountBalance2013-01-15 16:05:10.116 KVOTest[2199:907] <PersonObject: 0x20856180>2013-01-15 16:05:10.118 KVOTest[2199:907] {    kind = 1;    new = 2111;    old = 10;}

 

如有問題，請留言共同探討。