将 UI 元素添加到自定义 UIView

Question

我正在尝试添加一些UI元素，例如UIProgressView，UILabel，UIButton和UIActivityIndicator - 我认为代码是正确的(或者我是这么认为的(，但除了背景之外什么都没有显示。我做错了什么？

@interface LoadingView : UIView
@property (weak, nonatomic) IBOutlet UIActivityIndicatorView *activityIndicator;
@property (weak, nonatomic) IBOutlet UIProgressView *progressView;
@property (weak, nonatomic) IBOutlet UILabel *statusLabel;
@property (weak, nonatomic) IBOutlet UIButton *cancelButton;
- (void)removeLoadingView;
@end

@implementation LoadingView
@synthesize activityIndicator = _activityIndicator;
@synthesize progressView = _progressView;
@synthesize statusLabel = _statusLabel;
@synthesize cancelButton = _cancelButton;
- (UIView *)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        self.progressView = [[UIProgressView alloc] initWithFrame:CGRectMake(34, 225, 248, 9)];
        self.statusLabel = [[UILabel alloc] initWithFrame:CGRectMake(36, 257, 248, 31)];
        self.cancelButton = [[UIButton alloc] initWithFrame:CGRectMake(121, 317, 74, 37)];
        // Create a new image view, from the image made by our gradient method
        UIImageView *background = [[UIImageView alloc] initWithImage:[self addBackground]];
        background.alpha = 0.8;
        [self addSubview:background];
        self.activityIndicator = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
        // Set the resizing mask so it's not stretched
        self.activityIndicator.autoresizingMask =
        UIViewAutoresizingFlexibleTopMargin |
        UIViewAutoresizingFlexibleRightMargin |
        UIViewAutoresizingFlexibleBottomMargin |
        UIViewAutoresizingFlexibleLeftMargin;
        CGRect indicatorFrame = CGRectMake(142, 163, 37, 37);
        [self.activityIndicator setFrame:indicatorFrame];
        self.statusLabel.text = @"test 123";
        self.statusLabel.hidden = NO;
        self.statusLabel.enabled = YES;
        self.statusLabel.textColor = [UIColor whiteColor];
        [self addSubview:self.activityIndicator];
        [self addSubview:self.progressView];
        [self addSubview:self.cancelButton];
        [self addSubview:self.statusLabel];
        [self.activityIndicator startAnimating];
       /* // Create a new animation
        CATransition *animation = [CATransition animation];
        // Set the type to a nice wee fade
        [animation setType:kCATransitionFade];
        // Add it to the superView
        [[super layer] addAnimation:animation forKey:@"layerAnimation"];*/
    }
    return self;
}

- (UIImage *)addBackground{
    // Create an image context (think of this as a canvas for our masterpiece) the same size as the view
    UIGraphicsBeginImageContextWithOptions(self.bounds.size, YES, 1);
    // Our gradient only has two locations - start and finish. More complex gradients might have more colours
    size_t num_locations = 2;
    // The location of the colors is at the start and end
    CGFloat locations[2] = { 0.0, 1.0 };
    // These are the colors! That's two RBGA values
    CGFloat components[8] = {
        0.4,0.4,0.4, 0.8,
        0.1,0.1,0.1, 0.5 };
    // Create a color space
    CGColorSpaceRef myColorspace = CGColorSpaceCreateDeviceRGB();
    // Create a gradient with the values we've set up
    CGGradientRef myGradient = CGGradientCreateWithColorComponents (myColorspace, components, locations, num_locations);
    // Set the radius to a nice size, 80% of the width. You can adjust this
    float myRadius = (self.bounds.size.width*.8)/2;
    // Now we draw the gradient into the context. Think painting onto the canvas
    CGContextDrawRadialGradient (UIGraphicsGetCurrentContext(), myGradient, self.center, 0, self.center, myRadius, kCGGradientDrawsAfterEndLocation);
    // Rip the 'canvas' into a UIImage object
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    // And release memory
    CGColorSpaceRelease(myColorspace);
    CGGradientRelease(myGradient);
    UIGraphicsEndImageContext();
    // … obvious.
    return image;
}

编辑：所以我只是把代码放在viewDidload，现在什么都没有显示，甚至没有背景。我也在layoutSubviews中尝试了代码，结果与上面的代码相同，除了背景之外的所有内容都是隐藏的。

我用于从视图控制器实例化此视图的代码是;

@property (nonatomic, strong) LoadingView *loadingView;
@synthesize loadingView = _loadingView;
- (LoadingView *)loadingView
{
    if (!_loadingView) _loadingView = [[LoadingView alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    return _loadingView;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self.view addSubview:self.loadingView];
}

Answer 1

把它放到你的视图控制器viewDidLoad。这将确保您的主视图已经存在。

Answer 2

只有在发布@interface的代码后，我才意识到我正在使用weak指针创建元素。我将其更改为strong一切正常。谢谢大家的回答，我知道我没有显示整个代码，让大家感到困惑。

Answer 3

您是否在

您想要的地方调用了该方法initWithFrame:？

我认为您最好在方法init:中添加代码或-ViewDidLoad

Answer 4

尝试 self.cancelButton.backgroundColor = [UIColor redColor];看看是否有任何内容出现。

默认情况下，使用代码创建的自定义按钮没有背景图像或颜色，您需要手动指定它们。

Answer 5

你应该

在viewDidLoad中这样做- (void)layoutSubviews，或者如果你正在构建一个自定义UIView

Answer 6

您是否应该将新的 UI 元素添加到自我视图中，而不仅仅是自我视图。所以它看起来有点像这样：

 [[self view] addSubview:background];

而不是

 [self addSubview:background];

编辑

试试这个，看看控制器上的所有视图。

    for(UIView *vw in self.subviews) {
         NSLog(@"View : %@", vw);
    }

如果您无法访问 self.subviews，这意味着除了初始视图之外，您无法添加任何视图，因此您必须开始添加到 [self 视图]。尝试将 self.subviews 更改为 [[self view] 子视图];

您的背景视图可能已被放置为初始视图，因为它是 UIImageView，请尝试添加它。