ios - 以编程方式更改 UIImage 的 Alpha

Question

我仍在探索 xCode/Objective-C，我想知道如何才能更改 UIImage 的 alpha。我尝试编写自己的代码，但出现错误“在 UIImage 类型的对象上找不到属性‘alpha’”。如果我注释掉 alpha 更改行，启动画面会起作用。我的代码如下。

//
//  ViewController.m

#import "ViewController.h"

@interface ViewController ()

@property (nonatomic,weak) IBOutlet UIImage *logo;

@end

@implementation ViewController

ADBannerView *_bannerView;
- (void)viewDidLoad
{
    [super viewDidLoad];
    [self.view addSubview:_bannerView];

    [NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:@selector(showLogo:) userInfo:nil repeats:NO];

}

- (void)showLogo:(NSTimer *) timer{
    [UIView animateWithDuration:2.0 animations:^{
    self.logo.alpha = 1.0;
} completion:^(BOOL finished){

    [UIView animateWithDuration:2.0 animations:^{
        self.logo.alpha = 0.0;
    } completion:^(BOOL finished){
        ViewController *controller  = [self.storyboard instantiateViewControllerWithIdentifier:@"Menu"];
        [self.navigationController pushViewController:controller animated:YES];
    }];

}];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

//谢谢!

Answer 1

您需要更改包含它的 UIImageView 的 alpha，UIImage 没有 alpha 属性。