How to resize the image programmatically in objective-c in iphone

Question

I have an application where I am displaying large images in a small space. The images are quite large, but I am only displaying them in 100x100 pixel frames. My app is responding slowly because of the size fo the images I am using.

To improve performance, how can I resize the images programmatically using Objective-C?

Answer 1

Please find the following code.

- (UIImage *)imageWithImage:(UIImage *)image convertToSize:(CGSize)size {     UIGraphicsBeginImageContext(size);     [image drawInRect:CGRectMake(0, 0, size.width, size.height)];     UIImage *destImage = UIGraphicsGetImageFromCurrentImageContext();         UIGraphicsEndImageContext();     return destImage; } 

Answer 2

This code is for just change image scale not for resizing. You have to set CGSize as your image width and hight so the image will not stretch and it arrange at the middle.

- (UIImage *)imageWithImage:(UIImage *)image scaledToFillSize:(CGSize)size {     CGFloat scale = MAX(size.width/image.size.width, size.height/image.size.height);     CGFloat width = image.size.width * scale;     CGFloat height = image.size.height * scale;     CGRect imageRect = CGRectMake((size.width - width)/2.0f,                                   (size.height - height)/2.0f,                                   width,                                   height);      UIGraphicsBeginImageContextWithOptions(size, NO, 0);     [image drawInRect:imageRect];     UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();     UIGraphicsEndImageContext();     return newImage; }