在Iphone上有两种读取图片数据的简单方法: UIImageJPEGRepresentation和UIImagePNGRepresentation. UIImageJPEGRepresentation函数需要两个参数:图片的引用和压缩系数.而UIImagePNGRepresentation只需要图片引用作为参数.

方法一： 代码如下: – (UIImage*)scaleFromImage:(UIImage*)image scaledToSize:(CGSize)newSize {  CGSize imageSize = image.size;  CGFloat width = imageSize.width;  CGFloat height = imageSize.height;        if (width <= newSize.width && height <= newSize.