Test image rendering with kCAFilterTrilinear on iPhone 5C

ImageLoadVC.h

//
//  ImageLoadVC.h
//  touchtest

@import UIKit;

@interface ImageLoadVC : UIViewController

@end

ImageLoadVC.m

//
//  ImageLoadVC.m
//  touchtest

#import "ImageLoadVC.h"
@import Photos;

@interface ImageLoadVC ()

@property (nonatomic, strong) NSMutableArray<UIImageView *> *imageViews;
@property (nonatomic, strong) UIScrollView *scrollView;

@end

@implementation ImageLoadVC

- (void)viewDidLoad {
    _imageViews = [NSMutableArray array];
    _scrollView = [[UIScrollView alloc] initWithFrame:self.view.bounds];
    _scrollView.contentSize = (CGSize){ .width = self.view.bounds.size.width, .height = 550 };
    [self.view addSubview:_scrollView];
    
    // create a series of image views in different size.
    CGFloat lastTop = 0;
    for (int i=0; i < 10; ++i) {
        CGFloat h = (i+1)*10;
        UIImageView *imageView = [[UIImageView alloc] initWithFrame:(CGRect){.origin = {0, lastTop}, .size = {h,h}}];
        
        // applying these filters cause images not displayed properly on some resolution.
        imageView.layer.magnificationFilter = kCAFilterTrilinear;
        imageView.layer.minificationFilter = kCAFilterTrilinear;
        [_scrollView addSubview:imageView];
        [_imageViews addObject:imageView];
        lastTop += h;
    }
    
    [self loadPhoto];
}

- (void)loadPhoto {
    // get a photo from the album. 
    PHFetchResult<PHAsset *> *fetchResult = [PHAsset fetchAssetsWithOptions:nil];
    PHAsset *asset = [fetchResult lastObject];
    
    NSLog(@"image id is %@", asset.localIdentifier);
    
    PHImageRequestOptions *fetchOptions = [PHImageRequestOptions new];
    fetchOptions.resizeMode = PHImageRequestOptionsResizeModeFast;
    fetchOptions.deliveryMode = PHImageRequestOptionsDeliveryModeHighQualityFormat;
    
    for (int i=0; i<10; ++i) {
        CGFloat h = (i+1)*10;
        CGSize targetSize = {h,h};
        
        // repeat requesting image each time to see effects on different source images.
        [[PHImageManager defaultManager] requestImageForAsset:asset targetSize:targetSize contentMode:PHImageContentModeAspectFill options:fetchOptions resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {
            NSLog(@"image size is %@, targetSize is %@", NSStringFromCGSize(result.size), NSStringFromCGSize(targetSize));
            _imageViews[i].image = result;
        }];
    }
}

@end