小编Joe*_*Joe的帖子

这是来自Apple的iPhone"Utility Aplication"模板的未经修改的代码:

- (void)applicationDidFinishLaunching:(UIApplication *)application {

 MainViewController *aController = [[MainViewController alloc] initWithNibName:@"MainView" bundle:nil];
 self.mainViewController = aController;
 [aController release];

 mainViewController.view.frame = [UIScreen mainScreen].applicationFrame;
 [window addSubview:[mainViewController view]];
 [window makeKeyAndVisible];

}

当mainViewController被分配到aController时,self被指定的关键字:

 self.mainViewController = aController;

但是,mainViewController设置框架时,self不需要关键字:

 mainViewController.view.frame = [UIScreen mainScreen].applicationFrame;

如果我self从第一个示例中删除关键字,程序将崩溃并显示以下消息:

objc[1296]: FREED(id): message view sent to freed object=0x3b122d0

如果我将self关键字添加到第二个示例,程序运行正常.

任何人都可以解释为什么self在第一种情况下需要而不是第二种情况？我假设在两种情况下mainViewController都引用相同的实例变量.

我试图将UIlabel中的文本颜色与UIColor进行比较,但结果始终为false.

以下代码生成结果:

color equal 1, 0

我希望a和b都等于1.还有另一种方法可以做比较吗？

    bool a,b;

    UIColor *myColor1, *myColor2;

    myColor1 = [UIColor redColor];
    mainViewController.timerLabel.textColor = [UIColor redColor];

    myColor2 = [UIColor colorWithCGColor:mainViewController.timerLabel.textColor.CGColor];


    a = [[UIColor redColor] isEqual:myColor1];
    b = [[UIColor redColor] isEqual:myColor2];

    NSLog(@"color equal %i, %i",a,b);

我正在我的iphone应用程序中构建一个字典数组(称为键)来保存tableview的节名和行数.

代码如下所示:

[self.results removeAllObjects];
[self.keys removeAllObjects];

NSUInteger i,j = 0;
NSString *key = [NSString string];
NSString *prevKey = [NSString string];

if ([self.allResults count] > 0)
{
    prevKey = [NSString stringWithString:[[[self.allResults objectAtIndex:0] valueForKey:@"name"] substringToIndex:1]];

    for (NSDictionary *theDict in self.allResults)
    {
        key = [NSString stringWithString:[[theDict valueForKey:@"name"] substringToIndex:1]];

        if (![key isEqualToString:prevKey])
        {
            NSDictionary *newDictionary = [NSDictionary dictionaryWithObjectsAndKeys:
                                           [NSNumber numberWithInt:i],@"count",
                                           prevKey,@"section",
                                           [NSNumber numberWithInt:j],
                                           @"total",nil];

            [self.keys addObject:newDictionary];
            prevKey = [NSString stringWithString:key];
            i = 1;
        }
        else
        {
            i++;
        }
        j++;

    }

    NSDictionary *newDictionary = [NSDictionary …