實現一 使用一個繼承自UIView的類來包含要實現倒影效果的圖片，重寫這個UIView子類的繪圖方法，以實現圖片於倒影， 然後把這個View 添加到相應的地方顯示。 代碼： CKReflectionImage.h [cpp]   #import <UIKit/UIKit.h>      @interface CKReflectionImage : UIView {   @private              UIImage *image_;              /**       * Value of gradient start. This value is divided to height of image.       */       CGFloat visibleReflectionHeight_;              /**       * Padding to top image.       */       CGFloat paddingToTopImage_;   }         @property (nonatomic, readwrite, retain) UIImage *image;   @property (nonatomic, readwrite, assign) CGFloat visibleReflectionHeight;   @property (nonatomic, readwrite, assign) CGFloat paddingToTopImage;      @end   CKReflectionImage.h [cpp  #import "CKReflectionImage.h"      @implementation CKReflectionImage      #pragma mark -   #pragma mark Properties      @synthesize image = image_;   @synthesize visibleReflectionHeight = visibleReflectionHeight_;   @synthesize paddingToTopImage = paddingToTopImage_;      #pragma mark -   #pragma mark Memory management      - (void)dealloc {              [image_ release];       image_ = nil;              visibleReflectionHeight_ = 0.0f;              paddingToTopImage_ = 0.0f;              [super dealloc];          }      #pragma mark -   #pragma mark Draw methods      /**   * Draws the receiver’s image within the passed-in rectangle.   *    * @param rect: The portion of the view’s bounds that needs to be updated.   */   - (void)drawRect:(CGRect)rect {              [super drawRect:rect];              if (image_ != nil) {                      // Get current context to draw.           CGContextRef context = UIGraphicsGetCurrentContext();                      // Reflection image references           CGImageRef reflectionImage = NULL;           CGImageRef gradientImage = NULL;                      // Frame of image           CGRect frame = [self frame];           frame.origin.x = 0.0f;           frame.origin.y = 0.0f;           frame.size.width = CGRectGetWidth(frame);           frame.size.height = image_.size.height * CGRectGetWidth(frame) / image_.size.width;                      // Draw initial image in context           CGContextSaveGState(context);           {                              // Draw image in context, commented but the image show in reverse.   //            CGContextDrawImage(context, frame, [image_ CGImage]);                              // Push context to draw image.               UIGraphicsPushContext(context);                              // Draw original image in top               [image_ drawInRect:frame];                              // Pop to context               UIGraphicsPopContext();                          }           CGContextRestoreGState(context);                      // Create gradient bitmap           CGContextSaveGState(context);           {                              // Gradient is always black-white and the mask must be in the gray colorspace.               CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray();                              // Create a bitmap context               CGContextRef gradientContext = CGBitmapContextCreate(NULL, CGRectGetWidth(frame), CGRectGetHeight(frame), 8, 0, colorSpace, kCGImageAlphaNone);                              // Define the start and the end grayscale values (with the alpha, even though our               // bitmap context doesn't support alpha gradient requieres it).               CGFloat colors[] = {0.0f, 1.0f, 1.0f, 1.0f};                              // Creates the CGGradient               CGGradientRef grayScaleGradient = CGGradientCreateWithColorComponents(colorSpace, colors, NULL, 2);                              // Release colorSpace reference               CGColorSpaceRelease(colorSpace);                              // Create the start and end points for the gradient vector (straight down).               CGPoint gradientStartPoint = CGPointMake(0, (CGRectGetHeight(frame) - visibleReflectionHeight_));               CGPoint gradientEndPoint = CGPointMake(0, ((CGRectGetHeight(frame) * 2) - visibleReflectionHeight_));                              // Draw gradient into gradient context.               CGContextDrawLinearGradient(gradientContext, grayScaleGradient, gradientStartPoint, gradientEndPoint, kCGGradientDrawsAfterEndLocation);                              // Release Gradient reference.               CGGradientRelease(grayScaleGradient);                              // Convert the gradient context to image.               gradientImage = CGBitmapContextCreateImage(gradientContext);                              // Release gradient context               CGContextRelease(gradientContext);                          }           CGContextRestoreGState(context);                      // Apply gradient bitmap to new context that contains image.           CGContextSaveGState(context);           {                              // Create a RGB color space               CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();                              // Create bitmap context to join image and gradient context.               CGContextRef reflectionContext = CGBitmapContextCreate(NULL, CGRectGetWidth(frame), CGRectGetHeight(frame), 8, 0, colorSpace, (kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedLast));                              // Release color space               CGColorSpaceRelease(colorSpace);                              // First clip mask to context               CGContextSaveGState(context);               {                                      // Clip gradient mask to reflection context.                   CGContextClipToMask(reflectionContext, frame, gradientImage);                                  }               CGContextRestoreGState(context);                              // Second draw image to context               CGContextSaveGState(reflectionContext);               {                                      // Push context to draw image.                   UIGraphicsPushContext(reflectionContext);                                      // Draw original image in top                   [image_ drawInRect:frame];                                      // Pop to context                   UIGraphicsPopContext();                                  }               CGContextRestoreGState(reflectionContext);                              // Delete gradient image mask               CGImageRelease(gradientImage);                              // Convert reflection context to image.               reflectionImage = CGBitmapContextCreateImage(reflectionContext);                              // Release reflection context               CGContextRelease(reflectionContext);                          }           CGContextRestoreGState(context);                      // Transform matrix and draw reflection bitmap.           CGContextSaveGState(context);           {                              // Translate context matrix to height * 2 but next scale and sum 1.0f of image and padding.               CGContextTranslateCTM(context, CGRectGetMinX(frame), (CGRectGetHeight(frame) * 2) + paddingToTopImage_);                              // Flip vertical image in context.               CGContextScaleCTM(context, 1.0f, -1.0f);                              // Draw reflection image in context.               CGContextDrawImage(context, frame, reflectionImage);                              // Release reflectio image.               CGImageRelease(reflectionImage);                          }           CGContextRestoreGState(context);                  }          }      /**   * Set current image to another image.   *   * @param image: Another image to set.   */   - (void)setImage:(UIImage *)image {              if (image_ != image) {                      [image_ release];           image_ = [image retain];                  }              [self setNeedsDisplay];          }      /**   * Set current visibleReflectioHeight_ value to another.   *   * @param gradientStart: Another value to visible reflectio height variable.   */   - (void)setVisibleReflectionHeight:(CGFloat)visibleReflectioHeight {              if (visibleReflectionHeight_ != visibleReflectioHeight) {                      visibleReflectionHeight_ = visibleReflectioHeight;                  }              [self setNeedsDisplay];          }      /**   * Set current paddingToTopImage variable to another value.   *   * @param paddingToTopImage: Another value to padding to top image.   */   - (void)setPaddingToTopImage:(CGFloat)paddingToTopImage {              if (paddingToTopImage_ != paddingToTopImage) {                      paddingToTopImage_ = paddingToTopImage;                  }              [self setNeedsDisplay];          }      @end   使用： [cpp]   www.2cto.com CKReflectionImage *reflectionImage = [[CKReflectionImage alloc] initWithFrame:CGRectMake(96, 20, 128, 460)];      [reflectionImage setBackgroundColor:[UIColor clearColor]];      //set the padding of top image and its reflected image   [reflectionImage setPaddingToTopImage:5.0f];      // Hide 1/4 parts of image. show 3/4   [reflectionImage setVisibleReflectionHeight:(CGRectGetWidth([reflectionImage frame]) / 4 * 3)];      [reflectionImage setImage:[UIImage imageNamed:@"1.png"]];      [[self view] addSubview:reflectionImage];   實現效果   實現二 為UIImage添加一個關於倒影的category，以實現返回這個圖片， [cpp]   #import <UIKit/UIKit.h>         @interface UIImage (Reflection)      - (UIImage *)reflectionWithHeight:(int)height;   - (UIImage *)reflectionWithAlpha:(float)pcnt;   - (UIImage *)reflectionRotatedWithAlpha:(float)pcnt;      @end   UIImage+Reflection.h [cpp]  #import "UIImage+Reflection.h"      #ifndef UIImageReflectionMethods   #define UIImageReflectionMethods      CGImageRef CreateGradientImage (int pixelsWide, int pixelsHigh, CGFloat endPoint) {       CGImageRef theCGImage = NULL;              // gradient is always black-white and the mask must be in the gray colorspace       CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray();              // create the bitmap context       CGContextRef gradientBitmapContext = CGBitmapContextCreate(NULL, pixelsWide, pixelsHigh, 8, 0, colorSpace, kCGImageAlphaNone);              // define the start and end grayscale values (with the alpha, even though       // our bitmap context doesn't support alpha the gradient requires it)       CGFloat colors[] = {0.0, 1.0, 1, 1.0};              // create the CGGradient and then release the gray color space       CGGradientRef grayScaleGradient = CGGradientCreateWithColorComponents(colorSpace, colors, NULL, 2);       CGColorSpaceRelease(colorSpace);              // create the start and end points for the gradient vector (straight down)       CGPoint gradientStartPoint = CGPointZero;       CGPoint gradientEndPoint = CGPointMake(0, endPoint);              if (endPoint < 0) {           gradientEndPoint = CGPointMake(0, -endPoint);       }              // draw the gradient into the gray bitmap context       CGContextDrawLinearGradient(gradientBitmapContext, grayScaleGradient, gradientStartPoint, gradientEndPoint, kCGGradientDrawsAfterEndLocation);       CGGradientRelease(grayScaleGradient);              // convert the context into a CGImageRef and release the context       theCGImage = CGBitmapContextCreateImage(gradientBitmapContext);              if (endPoint < 0) {           // rotate           CGContextClearRect(gradientBitmapContext, CGRectMake(0, 0, pixelsWide, pixelsHigh));           CGContextTranslateCTM(gradientBitmapContext, 0.0, pixelsHigh);           CGContextScaleCTM(gradientBitmapContext, 1.0, -1.0);           CGContextDrawImage(gradientBitmapContext, CGRectMake(0, 0, pixelsWide, pixelsHigh), theCGImage);           CGImageRelease(theCGImage);           theCGImage = CGBitmapContextCreateImage(gradientBitmapContext);       }              CGContextRelease(gradientBitmapContext);              // return the imageref containing the gradient       return theCGImage;   }      static CGContextRef MyCreateBitmapContext (int pixelsWide, int pixelsHigh) {       CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();              // create the bitmap context       CGContextRef bitmapContext = CGBitmapContextCreate (NULL, pixelsWide, pixelsHigh, 8, 0, colorSpace, (kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst));       CGColorSpaceRelease(colorSpace);              return bitmapContext;   }      #endif      @implementation UIImage (Reflection)      - (UIImage *)reflectionRotatedWithAlpha:(float)pcnt {       int height = self.size.height;       UIImage * fromImage = self;       pcnt = 1.0 / pcnt;              // create a bitmap graphics context the size of the image       CGContextRef mainViewContentContext = MyCreateBitmapContext(fromImage.size.width, height);              // create a 2 bit CGImage containing a gradient that will be used for masking the        // main view content to create the 'fade' of the reflection.  The CGImageCreateWithMask       // function will stretch the bitmap image as required, so we can create a 1 pixel wide gradient       CGImageRef gradientMaskImage = CreateGradientImage(1, height, -(height * pcnt));              // create an image by masking the bitmap of the mainView content with the gradient view       // then release the  pre-masked content bitmap and the gradient bitmap       CGContextClipToMask(mainViewContentContext, CGRectMake(0.0, 0.0, fromImage.size.width, height), gradientMaskImage);       CGImageRelease(gradientMaskImage);              // In order to grab the part of the image that we want to render, we move the context origin to the       // height of the image that we want to capture, then we flip the context so that the image draws upside down.       // CGContextTranslateCTM(mainViewContentContext, 0.0, height);       // CGContextScaleCTM(mainViewContentContext, 1.0, -1.0);              // draw the image into the bitmap context       CGContextDrawImage(mainViewContentContext, CGRectMake(0, 0, fromImage.size.width, fromImage.size.height), [fromImage CGImage]);              // create CGImageRef of the main view bitmap content, and then release that bitmap context       CGImageRef reflectionImage = CGBitmapContextCreateImage(mainViewContentContext);       CGContextRelease(mainViewContentContext);              // convert the finished reflection image to a UIImage        UIImage * theImage = [UIImage imageWithCGImage:reflectionImage];       // image is retained by the property setting above, so we can release the original       CGImageRelease(reflectionImage);              return theImage;   }      - (UIImage *)reflectionWithHeight:(int)height {       if (height == -1) {           height = [self size].height;       }       if (height == 0)           return nil;              UIImage * fromImage = self;              // create a bitmap graphics context the size of the image       CGContextRef mainViewContentContext = MyCreateBitmapContext(fromImage.size.width, fromImage.size.height);              // create a 2 bit CGImage containing a gradient that will be used for masking the        // main view content to create the 'fade' of the reflection.  The CGImageCreateWithMask       // function will stretch the bitmap image as required, so we can create a 1 pixel wide gradient       CGImageRef gradientMaskImage = CreateGradientImage(1, height, height);              // create an image by masking the bitmap of the mainView content with the gradient view       // then release the  pre-masked content bitmap and the gradient bitmap       CGContextClipToMask(mainViewContentContext, CGRectMake(0.0, 0.0, fromImage.size.width, height), gradientMaskImage);       CGImageRelease(gradientMaskImage);              // In order to grab the part of the image that we want to render, we move the context origin to the       // height of the image that we want to capture, then we flip the context so that the image draws upside down.       CGContextTranslateCTM(mainViewContentContext, 0.0, fromImage.size.height);       CGContextScaleCTM(mainViewContentContext, 1.0, -1.0);              // draw the image into the bitmap context       CGContextDrawImage(mainViewContentContext, CGRectMake(0, 0, fromImage.size.width, fromImage.size.height), [fromImage CGImage]);              // create CGImageRef of the main view bitmap content, and then release that bitmap context       CGImageRef reflectionImage = CGBitmapContextCreateImage(mainViewContentContext);       CGContextRelease(mainViewContentContext);              // convert the finished reflection image to a UIImage        UIImage * theImage = [UIImage imageWithCGImage:reflectionImage];       // image is retained by the property setting above, so we can release the original       CGImageRelease(reflectionImage);              return theImage;   }      - (UIImage *)reflectionWithAlpha:(float)pcnt {       int height = self.size.height;       UIImage * fromImage = self;       pcnt = 1.0 / pcnt;              // create a bitmap graphics context the size of the image       CGContextRef mainViewContentContext = MyCreateBitmapContext(fromImage.size.width, height);              // create a 2 bit CGImage containing a gradient that will be used for masking the        // main view content to create the 'fade' of the reflection.  The CGImageCreateWithMask       // function will stretch the bitmap image as required, so we can create a 1 pixel wide gradient       CGImageRef gradientMaskImage = CreateGradientImage(1, height, height * pcnt);              // create an image by masking the bitmap of the mainView content with the gradient view       // then release the  pre-masked content bitmap and the gradient bitmap       CGContextClipToMask(mainViewContentContext, CGRectMake(0.0, 0.0, fromImage.size.width, height), gradientMaskImage);       CGImageRelease(gradientMaskImage);              // In order to grab the part of the image that we want to render, we move the context origin to the       // height of the image that we want to capture, then we flip the context so that the image draws upside down.       CGContextTranslateCTM(mainViewContentContext, 0.0, height);       CGContextScaleCTM(mainViewContentContext, 1.0, -1.0);              // draw the image into the bitmap context       CGContextDrawImage(mainViewContentContext, CGRectMake(0, 0, fromImage.size.width, fromImage.size.height), [fromImage CGImage]);              // create CGImageRef of the main view bitmap content, and then release that bitmap context       CGImageRef reflectionImage = CGBitmapContextCreateImage(mainViewContentContext);       CGContextRelease(mainViewContentContext);              // convert the finished reflection image to a UIImage        UIImage * theImage = [UIImage imageWithCGImage:reflectionImage];       // image is retained by the property setting above, so we can release the original       CGImageRelease(reflectionImage);              return theImage;   }      @end     使用非常簡單： [cpp]   [refView setImage:[image reflectionWithAlpha:0.5]];   [imageView setImage:[image reflectionWithHeight:50]];   [topRefView setImage:[image reflectionRotatedWithAlpha:0.5]];   效果