設置一個隨機應用程序背景圖像iOS 6

Question

我想爲我的應用程序設置一個隨機背景圖像，這樣每次有人啓動應用程序時都會顯示一個新的背景圖像。

Here's什麼香港專業教育學院試圖在- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 方法至今：

- (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:[myImageNames objectAtIndex:index]]; 
    self.window.backgroundColor = background; 
} 

我沒有得到任何錯誤，但我doesn't工作... 任何想法？ :)

Answer 1

試試這個：

- (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]; 
} 

Answer 2

，而不是委託類把這個代碼在主viewcontrller的initWithNibName方法：

- (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; 
} 

Answer 3

我認爲你缺少的東西在你的代碼，而你是從圖像設置背景顏色

請參閱[myImageNames objectAtIndex:index]，此代碼將返回正好的字符串對象。

因爲您只是將string傳遞給需要image的方法。

所以，你應該有一段代碼更改爲此

[UIImage imageNamed:[myImageNames objectAtIndex:index]。

現在你的代碼看起來像這樣

- (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]; 
} 

Answer 4

有你需要考慮兩件事情。首先，您需要通過UIImage，而不是NSString，至initWithPatternImage。該代碼應該是：

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]; 

的另一件事是，當iOS的實例主要故事板，它做了幾件事情你。其中一件事是分配並初始化self.window屬性，但它也會實例化包含在故事板中的主視圖控制器，並將其分配給UIWindow的rootViewController屬性。這意味着如果你的主視圖控制器創建了一個UIView（幾乎每個視圖控制器都會這樣做），它的背景將視覺覆蓋背景，除非它被設置爲透明。由於設置透明UIView可能不是你想要的，並且它的方式很尷尬，我建議在@Dilip答案後面設置背景到你的根視圖控制器的視圖。

Answer 5

我得到了我的工作，謝謝大家回覆，謝謝大家！

的代碼應該是：

- (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; 
}