在iOS 6上设置随机应用程序背景图像

我想为我的应用程序设置一个随机背景图像，这样每当有人启动应用程序时，都会显示一个新的背景图像

以下是我迄今为止在

-（BOOL）应用程序中尝试的内容：（UIApplication*）应用程序使用选项完成启动：（NSDictionary*）启动选项

方法：

我没有错误，但我不工作。。。 有什么想法吗？

---

：）

将此代码放在主视图控件的initWithNibName方法中，而不是委托类：

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {

        NSMutableArray *myImageNames = [NSMutableArray arrayWithObjects:@"image1.png", @"image2.png", @"image3.png",@"image4.png", @"image5.png",@"image6.png",   nil];
        int index = arc4random() % [myImageNames count];

        self.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:[myImageNames objectAtIndex:index]]];
    }
    return self;
}

试试这个：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    NSMutableArray *myImageNames = [NSMutableArray arrayWithObjects:@"image1.png", @"image2.png", @"image3.png", nil];
   int index = arc4random() % [myImageNames count];
   UIColor *background = [[UIColor alloc] initWithPatternImage:[UIImage imageNamed:[myImageNames objectAtIndex:index]]];
   self.window.backgroundColor = background;
   [background release];
}

---

我认为在设置图像的背景色时，代码中缺少了一些内容

请参见

[myImageNames objectAtIndex:index]

，此代码将返回just string对象

因为您只是将

字符串

传递给需要

图像的方法

所以你应该把这段代码改成这个

[UIImage ImageName:[myImageNames对象索引：索引]

现在，您的代码将如下所示

 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
 {
   NSMutableArray *myImageNames = [NSMutableArray arrayWithObjects:@"image1.png", @"image2.png", @"image3.png", nil];
  int index = arc4random() % [myImageNames count];
  UIColor *background = [[UIColor alloc] initWithPatternImage:[UIImage imageNamed:  [myImageNames objectAtIndex:index]]];
  self.window.backgroundColor = background;
  [background release];
}

---

有两件事需要考虑。首先，您需要通过<代码> UIImage <代码>，而不是<代码> NScord，以“模式NoSimule”<代码> > In。代码应该是：

 NSMutableArray *myImageNames = [NSMutableArray arrayWithObjects:@"image1.png", @"image2.png", @"image3.png", nil];
  int index = arc4random() % [myImageNames count];
  UIColor *background = [[UIColor alloc] initWithPatternImage:[UIImage imageNamed:  [myImageNames objectAtIndex:index]]];
  self.window.backgroundColor = background;
  [background release];

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    NSMutableArray *myImageNames = [NSMutableArray arrayWithObjects:@"image1.jpg", @"image2.jpg", @"image3.png", nil];
    int index = arc4random() % [myImageNames count];
    UIColor *background = [[UIColor alloc] initWithPatternImage:[UIImage imageNamed:[myImageNames objectAtIndex:index]]];
    self.window.backgroundColor = background;
    // Override point for customization after application launch.
    return YES;
}

---

另一件事是，当iOS实例化主情节提要时，它会为您做一些事情。其中之一是分配和初始化

self.window

属性，但它也实例化了包含在情节提要中的主视图控制器，并将其分配给

UIWindow

的

rootViewController

这意味着如果主视图控制器创建一个

UIView

（几乎每个视图控制器都这样做），它的背景将在视觉上覆盖

ui窗口

背景，除非它设置为透明。由于设置透明的

ui视图

可能不是您想要的，顺便说一句，这很尴尬，我建议在@Dilip answer之后，将背景设置为根视图控制器的视图。

我之所以能工作，是因为所有这些你们回答说，谢谢大家

代码应为：

 NSMutableArray *myImageNames = [NSMutableArray arrayWithObjects:@"image1.png", @"image2.png", @"image3.png", nil];
  int index = arc4random() % [myImageNames count];
  UIColor *background = [[UIColor alloc] initWithPatternImage:[UIImage imageNamed:  [myImageNames objectAtIndex:index]]];
  self.window.backgroundColor = background;
  [background release];

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    NSMutableArray *myImageNames = [NSMutableArray arrayWithObjects:@"image1.jpg", @"image2.jpg", @"image3.png", nil];
    int index = arc4random() % [myImageNames count];
    UIColor *background = [[UIColor alloc] initWithPatternImage:[UIImage imageNamed:[myImageNames objectAtIndex:index]]];
    self.window.backgroundColor = background;
    // Override point for customization after application launch.
    return YES;
}