iPhone 实现图片的倒影

在 viewDidLoad 方法中添加以下代码 

- (void)viewDidLoad {
    
    [super viewDidLoad]; 
    
    [[[self view] layer] setBackgroundColor:[[UIColor blackColor] CGColor]]; 
    
    UIImage *balloon = [UIImage imageNamed:@"b.jpg"];

    CALayer *topLayer = [[CALayer alloc] init]; 
    
    [topLayer setBounds:CGRectMake(0.0f, 0.0f, 320.0, 240)]; 
    
    [topLayer setPosition:CGPointMake(160.0f, 120.0f)]; 
    
    [topLayer setContents:(id)[balloon CGImage]];

    [[[self view] layer] addSublayer:topLayer];

    CALayer *reflectionLayer = [[CALayer alloc] init]; 
    
    [reflectionLayer setBounds:CGRectMake(0.0f, 0.0f, 320.0, 240.0)]; 
    
    [reflectionLayer setPosition:CGPointMake(160.0f, 310.0f)];

    [reflectionLayer setContents:[topLayer contents]];

    [reflectionLayer setValue:[NSNumber numberWithFloat:180.0] forKeyPath:@"transform.rotation.x"];

    CAGradientLayer *gradientLayer = [[CAGradientLayer alloc] init]; 
    
    [gradientLayer setBounds:[reflectionLayer bounds]]; 
    
    [gradientLayer setPosition:CGPointMake([reflectionLayer bounds].size.width/2, [reflectionLayer bounds].size.height/2)];
    
    [gradientLayer setColors:[NSArray arrayWithObjects: (id)[[UIColor clearColor] CGColor],(id)[[UIColor blackColor] CGColor], nil]];

    [gradientLayer setStartPoint:CGPointMake(0.5,0.35)]; 
    
    [gradientLayer setEndPoint:CGPointMake(0.5,1.0)];

    [reflectionLayer setMask:gradientLayer];

    [[[self view] layer] addSublayer:reflectionLayer];
}