版本记录

前言

分类有很多好用的地方，原生的API不支持的地方可以写个分类实现自己想要的功能，接下来就简单的写一个UIImage的分类。

简单的UIImage分类

1. UIImage+JJUIImageCategory.h

#import <UIKit/UIKit.h>

@interface UIImage (JJUIImageCategory)

+ (UIImage *)sd_animatedGIFNamed:(NSString *)name;

+ (UIImage *)jj_sd_animatedGIFWithData:(NSData *)data;

- (UIImage *)sd_animatedImageByScalingAndCroppingToSize:(CGSize)size;

@end

2. UIImage+JJUIImageCategory.m

#import "UIImage+JJUIImageCategory.h"
#import <ImageIO/ImageIO.h>

@implementation UIImage (JJUIImageCategory)

+ (UIImage *)jj_sd_animatedGIFWithData:(NSData *)data 
{
    if (!data) {
        return nil;
    }
    
    CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFDataRef)data, NULL);
    
    size_t count = CGImageSourceGetCount(source);
    
    UIImage *animatedImage;
    
    if (count <= 1) {
        animatedImage = [[UIImage alloc] initWithData:data];
    }
    else {
        NSMutableArray *images = [NSMutableArray array];
        
        NSTimeInterval duration = 0.0f;
        
        for (size_t i = 0; i < count; i++) {
            CGImageRef image = CGImageSourceCreateImageAtIndex(source, i, NULL);
            
            duration += [self sd_frameDurationAtIndex:i source:source];
            
            [images addObject:[UIImage imageWithCGImage:image scale:[UIScreen mainScreen].scale orientation:UIImageOrientationUp]];
            
            CGImageRelease(image);
        }
        
        if (!duration) {
            duration = (1.0f / 10.0f) * count;
        }
        
        animatedImage = [UIImage animatedImageWithImages:images duration:duration];
    }
    
    CFRelease(source);
    
    return animatedImage;
}

+ (float)sd_frameDurationAtIndex:(NSUInteger)index source:(CGImageSourceRef)source 
{
    float frameDuration = 0.1f;
    CFDictionaryRef cfFrameProperties = CGImageSourceCopyPropertiesAtIndex(source, index, nil);
    NSDictionary *frameProperties = (__bridge NSDictionary *)cfFrameProperties;
    NSDictionary *gifProperties = frameProperties[(NSString *)kCGImagePropertyGIFDictionary];
    
    NSNumber *delayTimeUnclampedProp = gifProperties[(NSString *)kCGImagePropertyGIFUnclampedDelayTime];
    if (delayTimeUnclampedProp) {
        frameDuration = [delayTimeUnclampedProp floatValue];
    }
    else {
        
        NSNumber *delayTimeProp = gifProperties[(NSString *)kCGImagePropertyGIFDelayTime];
        if (delayTimeProp) {
            frameDuration = [delayTimeProp floatValue];
        }
    }
    
    // Many annoying ads specify a 0 duration to make an image flash as quickly as possible.
    // We follow Firefox's behavior and use a duration of 100 ms for any frames that specify
    // a duration of <= 10 ms. See <rdar://problem/7689300> and <http://webkit.org/b/36082>
    // for more information.
    
    if (frameDuration < 0.011f) {
        frameDuration = 0.100f;
    }
    
    CFRelease(cfFrameProperties);
    return frameDuration;
}

+ (UIImage *)sd_animatedGIFNamed:(NSString *)name 
{
    CGFloat scale = [UIScreen mainScreen].scale;
    
    if (scale > 1.0f) {
        NSString *retinaPath = [[NSBundle mainBundle] pathForResource:[name stringByAppendingString:@"@2x"] ofType:@"gif"];
        
        NSData *data = [NSData dataWithContentsOfFile:retinaPath];
        
        if (data) {
            return [UIImage jj_sd_animatedGIFWithData:data];
        }
        
        NSString *path = [[NSBundle mainBundle] pathForResource:name ofType:@"gif"];
        
        data = [NSData dataWithContentsOfFile:path];
        
        if (data) {
            return [UIImage jj_sd_animatedGIFWithData:data];
        }
        
        return [UIImage imageNamed:name];
    }
    else {
        NSString *path = [[NSBundle mainBundle] pathForResource:name ofType:@"gif"];
        
        NSData *data = [NSData dataWithContentsOfFile:path];
        
        if (data) {
            return [UIImage jj_sd_animatedGIFWithData:data];
        }
        
        return [UIImage imageNamed:name];
    }
}

- (UIImage *)sd_animatedImageByScalingAndCroppingToSize:(CGSize)size 
{
    if (CGSizeEqualToSize(self.size, size) || CGSizeEqualToSize(size, CGSizeZero)) {
        return self;
    }
    
    CGSize scaledSize = size;
    CGPoint thumbnailPoint = CGPointZero;
    
    CGFloat widthFactor = size.width / self.size.width;
    CGFloat heightFactor = size.height / self.size.height;
    CGFloat scaleFactor = (widthFactor > heightFactor) ? widthFactor : heightFactor;
    scaledSize.width = self.size.width * scaleFactor;
    scaledSize.height = self.size.height * scaleFactor;
    
    if (widthFactor > heightFactor) {
        thumbnailPoint.y = (size.height - scaledSize.height) * 0.5;
    }
    else if (widthFactor < heightFactor) {
        thumbnailPoint.x = (size.width - scaledSize.width) * 0.5;
    }
    
    NSMutableArray *scaledImages = [NSMutableArray array];
    
    UIGraphicsBeginImageContextWithOptions(size, NO, 0.0);
    
    for (UIImage *image in self.images) {
        [image drawInRect:CGRectMake(thumbnailPoint.x, thumbnailPoint.y, scaledSize.width, scaledSize.height)];
        UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
        
        [scaledImages addObject:newImage];
    }
    
    UIGraphicsEndImageContext();
    
    return [UIImage animatedImageWithImages:scaledImages duration:self.duration];
}

@end

这里：

• 第一个是加载指定名字的图片。
• 第二个是加载指定NSData数据类型的图片。
• 第三个是根据指定尺寸对图片进行缩放。

后记

本篇已结束，后面更精彩~~~~