CGBitmapContextCreateImage or CGContextDrawImage doesn't work - objective-c

Question

I can't solve this problem. Load image, convert to CGImageRef. Try to get bitmap context and render on the screen.
NSURL *imageFileURL = [NSURL fileURLWithPath:stringIMG];
CGImageSourceRef imageSource = CGImageSourceCreateWithURL((CFURLRef)imageFileURL, NULL);
CGImageRef imageRef = CGImageSourceCreateImageAtIndex(imageSource, 0, NULL);
NSInteger bitsPerComponent = CGImageGetBitsPerComponent(imageRef);
NSInteger bitsPerPixel = CGImageGetBitsPerPixel(imageRef);
CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(imageRef);
NSInteger bytesPerRow = CGImageGetBytesPerRow(imageRef);
NSInteger width = CGImageGetWidth(imageRef);
NSInteger height = CGImageGetHeight(imageRef);
CGColorSpaceRef colorspace = CGImageGetColorSpace(imageRef);
size_t rawData = bytesPerRow*height;
unsigned char *data = malloc(rawData);
memset(data2, 0, rawData);
CGContextRef context = CGBitmapContextCreate(data, width, height, bitsPerComponent, bytesPerRow, colorspace, bitmapInfo);
CGImageRef imageRef2 = CGBitmapContextCreateImage(context);
// CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef2);
UIImage *result = [UIImage imageWithCGImage:imageRef2];//if i do like this i got white empty screen
UIImageView *image = [[UIImageView alloc] initWithImage:result];
[self.view addSubview:image];// if i do like this i got black rectangle on the white screen
I have no idea. I check by breakpoint that context is not null. I don't know what should i do. Please maybe anyone can help me?

Answer 1

Category added it to UIImage for resizing using CoreGraphics
UIImage+Resize.h
#import <UIKit/UIKit.h>
#interface UIImage (Resizing)
-(UIImage*)resizedImageWithSize:(CGSize)size;
#end
UIImage+Resizing.m
#import "UIImage+Resizing.h"
#implementation UIImage (Resizing)
-(UIImage*)resizedImageWithSize:(CGSize)size {
CGImageRef cgImage = [self CGImage];
size_t bitsPerComponent = CGImageGetBitsPerComponent(cgImage);
size_t bytesPerRow = CGImageGetBytesPerRow(cgImage);
CGColorSpaceRef colorSpace = CGImageGetColorSpace(cgImage);
CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(cgImage);
CGContextRef context = CGBitmapContextCreate(nil, size.width, size.height, bitsPerComponent, bytesPerRow, colorSpace, bitmapInfo);
CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
CGContextDrawImage(context, CGRectMake(0, 0, size.width, size.height), cgImage);
CGImageRef resizedImageRef = CGBitmapContextCreateImage(context);
UIImage *resizedImage = [UIImage imageWithCGImage:resizedImageRef];
CFRelease(resizedImageRef);
CFRelease(context);
return resizedImage;
}
#end