"[[UIScreen mainScreen] bounds]"返回null？

Question

当我尝试获取主屏幕的边界时[[UIScreen mainScreen] bounds],它返回null.我也尝试过[[UIScreen applicationFrame] bounds],仍然返回null.

奇怪的是; 如果我这样做NSLog(@"%@", [UIScreen mainScreen]);打印出正确的界限,虽然我不知道如何解析它,如果它甚至可能.

这是相关的代码:

-(void)loadView {
    [super loadView];
    CGRect pagingFrame = [[UIScreen mainScreen] bounds]; 
    NSLog(@"%@", [[UIScreen mainScreen] bounds]); //prints null for me
    NSLog(@"Width of original frame = %d", pagingFrame.size.width); //prints out 0
    pagingFrame.origin.x -= pagingXOrigin;
    pagingFrame.size.width += pagingWidthAdd;
    NSLog(@"Width of adjusted frame = %d", pagingFrame.size.width); //still prints out 0
    pagingScrollView = [[UIScrollView alloc] initWithFrame:pagingFrame];
    pagingScrollView.pagingEnabled = YES;
    pagingScrollView.backgroundColor = [UIColor blackColor];
    pagingScrollView.contentSize = CGSizeMake(pagingFrame.size.width * [self imageCount], pagingFrame.size.height);
    self.view = pagingScrollView;
    //Initialize sets
    recycled = [[NSMutableSet alloc] init];
    visible = [[NSMutableSet alloc] init];
    [self tilePages];
}

pagingScrollView 在头文件中声明,循环和可见.

我正在使用Xcode 3和iOS SDK 4.1.

我确信这有一个非常简单的解决方案,但是我仍然是Objective-C的新手,因此我无法解决它.

谢谢

Answer 1

该NSStringFromCGRect方法使得快速记录CGRect变得更加容易.有关详细信息,请参阅Apple的文档,但这是一段代码:

CGRect screenBounds = [[UIScreen mainScreen] bounds];
NSLog(@"%@", NSStringFromCGRect(screenBounds));

Answer 2

bounds是一个struct,而不是一个对象.您无法使用%@格式说明符输出它.同样,结构的成员是浮点数,而不是整数.如果输出它们%d,你肯定会得到错误的结果.