iphone - 在 iPhone App 首次启动时显示信息 imageview

Question

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Answer 1

1. 检查 NSUserDefaults 之前是否显示(和关闭)帮助 View
2. 创建 UIImageView 并将其添加到您的 View
3. 将 UITapGestureRecognizer 添加到 imageView
4. 在点击手势的操作中删除帮助 View 并将 View 已关闭的信息保存到 NSUserDefaults。

.

- (void)viewDidLoad {
    [super viewDidLoad];
    if (![[NSUserDefaults standardUserDefaults] boolForKey:@"didDisplayHelpScreen"]) {
        UIWindow *window = [[[UIApplication sharedApplication] windows] lastObject];

        UIImageView *imageView = [[UIImageView alloc] initWithFrame:window.bounds];
        imageView.image = [UIImage imageNamed:@"78-stopwatch"];
        imageView.backgroundColor = [UIColor greenColor];
        imageView.alpha = 0.5;
        UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(dismissHelpView:)];
        [imageView addGestureRecognizer:tapGesture];
        imageView.userInteractionEnabled = YES;
        [window addSubview:imageView];
    }
}

- (void)dismissHelpView:(UITapGestureRecognizer *)sender {
    UIView *helpImageView = sender.view;
    [helpImageView removeFromSuperview];
    [[NSUserDefaults standardUserDefaults] setBool:YES forKey:@"didDisplayHelpScreen"];
}