iphone - 从另一个类调用时对象为零

Question

我想在另一个类中调用方法时更改另一个对象的属性。

更改此对象属性的代码位于第一个类的方法中，并且在从它自己的类调用它时有效，但是当从其他类调用时，方法中的对象返回 nil。

代码如下:

ViewController.h

@interface ViewController : UIViewController {

    UIView *menuView; //the object

}

@property (nonatomic, retain) IBOutlet UIView *menuView;

-(void)closeMenu; //the method

@end

ViewController.m

@implementation ViewController

@synthesize menuView;

-(void)closeMenu{

    [menuView setFrame:CGRectMake(menuView.frame.origin.x, -menuView.frame.size.height, menuView.frame.size.width, menuView.frame.size.height)];

    NSLog(@"%f", menuView.frame.size.height); //returns height when method is called from it's own class. But returns 0 (nil) when called from the other class.

}

SDNestedTableViewController.h(没什么太重要，但可能有帮助？)

@interface SDMenuViewController : SDNestedTableViewController{


}

SDNestedTableViewController.m

#import "SDMenuViewController.h"
#import "ViewController.h"

- (void) item:(SDGroupCell *)item subItemDidChange:(SDSelectableCell *)subItem
{

    ViewController *firstViewController = [[[ViewController alloc] init] autorelease];

    SelectableCellState state = subItem.selectableCellState;
    NSIndexPath *indexPath = [item.subTable indexPathForCell:subItem];
    switch (state) {
        case Checked:
            NSLog(@"Changed Sub Item at indexPath:%@ to state \"Checked\"", indexPath);


            [firstViewController closeMenu]; //called from other class


            break;
        case Unchecked:
            NSLog(@"Changed Sub Item at indexPath:%@ to state \"Unchecked\"", indexPath);
            break;
        default:
            break;
    }
}

Answer 1

您发布的内容看起来像:

-(void)closeMenu{
    // menuView is never initialized, == nil
    [nil setFrame:CGRectMake(0, -0, 0, 0)];

    NSLog(@"%f", 0); //returns height when method is called from it's own class. But returns 0 (nil) when called from the other class.

}

所以你在做 NSLog(@"%f", 0);。

如果您通过访问 view 属性加载 View ，则 menuView 将由 IB 规则初始化。有关 viewController View 加载/卸载的详细信息，请参阅 reference docs .