如何在导航栏中创建一个带有UIActivityIndi​​cator的按钮,其样式与普通按钮相同？

我在这里和其他网站上看到的所有示例都涉及创建UIActivityIndi​​catorView并使用以下内容加载它:

self.navigationItem.rightBarButtonItem = [[[UIBarButtonItem alloc] 
                   initWithCustomView:myActivityIndicatorView 
                   target:nil 
                   action:nil] 
                  autorelease];

但是,这只是在导航栏中创建一个普通活动指示器.我想要做的是有一个看起来像普通的UIBarButtonSystemItem按钮,但有一个活动指示器,而不是一个默认图像.我尝试使用nil图像或标题执行initWithImage和initWithTitle,然后将活动指示符添加为子视图,但这不起作用.

有任何想法吗？

我的解决方案是创建UIButton的子类:

在SOActivityButton.h中:

@interface SOActivityButton : UIButton 
{
UIActivityIndicatorView* activityIndicator;
}
@end

在SOActivityButton.m中:

@implementation SOActivityButton

- (id)initWithFrame:(CGRect)frame 
{
    if (self = [super initWithFrame:frame]) 
    {
        CGRect innerFrame = CGRectInset(frame, 8.0f, 8.0f);
        activityIndicator = [[UIActivityIndicatorView alloc]
                                    initWithFrame:innerFrame];
        activityIndicator.activityIndicatorViewStyle = UIActivityIndicatorViewStyleWhite;
        [self addSubview:activityIndicator];
    }
    return self;
}

- (void)dealloc 
{
    [activityIndicator release], activityIndicator = nil;
    [super dealloc];
}

- (void) startAnimating
{   
    [activityIndicator startAnimating];
}

- (void) stopAnimating
{   
    [activityIndicator stopAnimating];
}
@end

然后使用它:

SOActivityButton* activityButton = [[SOActivityButton alloc] 
                    initWithFrame:CGRectMake(0.0f, 0.0f, 32.0f, 32.0f)];
[activityButton setImage:[UIImage imageNamed:@"button-background.png"]
                    forState:UIControlStateNormal];
[activityButton addTarget:self action:@selector(myAction:) 
                    forControlEvents:UIControlEventTouchUpInside];
UIBarButtonItem *activityBarButtonItem = [[UIBarButtonItem alloc] 
                    initWithCustomView:activityButton];
[activityButton release];
self.navigationItem.rightBarButtonItem = activityBarButtonItem;
[activityBarButtonItem release];

您需要找到或创建一个button-background.png.这里的PSD 应该有一个.