如何重新显示iPhone编程（Xcode）

Question

我是iOS编程的初学者。 我想逐帧显示屏幕上的图像。 但在我的源代码中，只有第一帧在屏幕上绘制并忽略了所有下一帧。 如何实时重新显示？

我的图像显示来源：
- viewDidLoad：init显示第一个屏幕
- ChangeImage：更改显示下一个屏幕
- setPixelColorR：G：B：X：Y ::更改屏幕上的像素颜色

<ContentViewController.h>
#import <UIKit/UIKit.h>

@interface ContentViewController : UIViewController {
    IBOutlet UIImageView *svContent;

    CGContextRef context;
    size_t dataSize;

    UInt8* initdata;

}


@property(nonatomic,retain) IBOutlet UIImageView *svContent;

-(IBAction)btnPhotosTouched;

- (void) ChangeImage;

- (void) setPixelColorR:(int)red G:(int)green B:(int)blue X:(int)x Y:(int)y;

@end

和

<ContentViewController.m>
#import "ContentViewController.h"


@implementation ContentViewController
@synthesize svContent;

- (void)viewDidLoad {
    [super viewDidLoad];

    UIImageView *imageView;

    CGSize screenSize = [[UIScreen mainScreen] bounds].size;

    CGFloat width = screenSize.width;
    CGFloat height = screenSize.height;
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

    size_t bitsPerComponent = 8;
    size_t bytesPerPixel = 4;
    size_t bytesPerRow = (width * bitsPerComponent * bytesPerPixel + 7) / 8;
    dataSize = bytesPerRow * height;

    initdata = malloc(sizeof(UInt8) * dataSize);
    memset(initdata, 0, dataSize);

    context = CGBitmapContextCreate(initdata, width, height, bitsPerComponent, bytesPerRow, colorSpace, kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrder32Big);


    // a drawing for a test.
    CGContextSetRGBFillColor (context, 1, 0, 0, 1);
    CGContextFillRect (context, CGRectMake (0, 0, 200, 100 ));
    CGContextSetRGBFillColor (context, 0, 0, 1, .5);
    CGContextFillRect (context, CGRectMake (0, 0, 100, 200));



    CGColorSpaceRelease(colorSpace);
    CGImageRef imageRef = CGBitmapContextCreateImage(context);
    UIImage *result = [[UIImage imageWithCGImage:imageRef] retain];
    CGImageRelease(imageRef);


    imageView = [[UIImageView alloc] initWithImage:result];

    [svContent addSubview:imageView];
    [imageView release];

//  [self ChangeImage:initdata];
}

- (void) ChangeImage
{
    UIImageView *imageView;

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();


    CGColorSpaceRelease(colorSpace);
    CGImageRef imageRef = CGBitmapContextCreateImage(context);
    UIImage *result = [[UIImage imageWithCGImage:imageRef] retain];
    CGImageRelease(imageRef);


    imageView = [[UIImageView alloc] initWithImage:result];

    [svContent addSubview:imageView];

    [imageView release];
    NSLog(@"Thread Image Change GO");
    [svContent setNeedsDisplay];
    [self.view setNeedsDisplay];
    [super.view setNeedsDisplay];
}

- (void) setPixelColorR:(int)red G:(int)green B:(int)blue X:(int)x Y:(int)y
{
    CGFloat r = (CGFloat)red / 255.0f;
    CGFloat g = (CGFloat)green / 255.0f;
    CGFloat b = (CGFloat)blue / 255.0f;


    CGContextSetRGBFillColor(context, r, g, b, 1);
    CGContextFillRect(context, CGRectMake(x, y, 1, 1));
}

.
.
.

@end

谢谢。