子类化 UIActivityIndi​​cator 以更改图像

Question

这就是我所做的：

@implementation BGUIActivityIndicator

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code
    }
    [self customInitialize];
    return self;
}

-(id)initWithCoder:(NSCoder *)aDecoder
{
    self = [super initWithCoder:aDecoder];
    [self customInitialize];
    return self;
}

-(void)customInitialize
{
    UIView * theImageView= [self findASubViewforClass:[UIImageView class]];//
    UIImageView * theImageView1 = (UIImageView *) theImageView;
    theImageView1.image = [UIImage imageNamed:@"spinner_blue"];
    [theImageView1.image saveScreenshot];
    while (false) ;
}
/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
    // Drawing code
}
*/

@end

一切看起来都很完美。 [theImageView1.image saveScreenshot];完美记下新旧观点。

但是，没有任何变化。为什么？

我并不是在问如何更改 UIActivityIndi​​cator 的图像。已经有很多了。我想通过继承 UIActivityIndi​​cator 来使用它，因为我认为它是最优雅的解决方案。我好像做不到。

特别是，我在问为什么我的方法（例如，用于更改搜索控制器的背景）不适用于此。

Answer 1

根据UIActivityIndicatorView Class Reference，没有办法/机会通过子分类来改变图像。

但是您可以更改其 activityIndi​​catorViewStyle 、活动指示器的颜色、UIActivityIndi​​catorStyle 等。

我认为，在没有子类化的情况下，类 UIImageView 提供了一种非常有用且简单的方法来实现这样的事情。您唯一需要做的就是：

1.Provide a number of images that reflect your indicator animation.
2.Create a new UIImageView instance and set images and animation duration.
3.Position your custom activity indicator within your current view.

示例代码：

//Create the first status image and the indicator view
UIImage *statusImage = [UIImage imageNamed:@"status1.png"];
UIImageView *activityImageView = [[UIImageView alloc] 
                initWithImage:statusImage];


//Add more images which will be used for the animation
activityImageView.animationImages = [NSArray arrayWithObjects:
            [UIImage imageNamed:@"status1.png"],
            [UIImage imageNamed:@"status2.png"],
            [UIImage imageNamed:@"status3.png"],
            [UIImage imageNamed:@"status4.png"],
            [UIImage imageNamed:@"status5.png"],
            [UIImage imageNamed:@"status6.png"],
            [UIImage imageNamed:@"status7.png"],
            [UIImage imageNamed:@"status8.png"],
            nil];


//Set the duration of the animation (play with it
//until it looks nice for you)
activityImageView.animationDuration = 0.8;


//Position the activity image view somewhere in 
//the middle of your current view
activityImageView.frame = CGRectMake(
            self.view.frame.size.width/2
                -statusImage.size.width/2, 
            self.view.frame.size.height/2
                -statusImage.size.height/2, 
            statusImage.size.width, 
            statusImage.size.height);

//Start the animation
[activityImageView startAnimating];


//Add your custom activity indicator to your current view
[self.view addSubview:activityImageView];

查看完整详情Here