Image I/O

Image I/O 是 iOS SDK 提供的一个图片编解码器，支持 JPEG, JPEG2000, RAW, TIFF, BMP, GIF, and PNG ，支持 metadata 读取，提供颜色管理。

CGImageSource ：数据读取的接口，支持 URL, CFData, or data consumer 。提供读取 CGImage, Thumbnail CGImage, image properties 等等。

CGImageDestination：数据写入的接口，支持 URL, CFData, or data consumer 。可写入单个或多个 CGImage, 包括 Thumbnail CGImage, image properties等。

#import "ViewController.h"
#import "GifView.h"

@interface ViewController ()

@property (nonatomic, strong) GifView *gifView;

@end

@implementation ViewController

- (void)viewDidLoad {
[super viewDidLoad];

//将资源文件打包
NSString *bundlePath = [[NSBundle mainBundle] pathForResource:@"Source.bundle" ofType:nil];
NSBundle *bundle = [NSBundle bundleWithPath:bundlePath];

NSString *filePath = [bundle pathForResource:@"info.plist" ofType:nil];
NSArray  *dataArr = [NSArray arrayWithContentsOfFile:filePath];

NSDictionary *dict = dataArr[0];

NSString *gifPath = [bundle pathForResource:dict[@"png"] ofType:nil];

UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageWithContentsOfFile:gifPath]];
imageView.userInteractionEnabled = YES;
imageView.center = CGPointMake(150, 150);
[self.view addSubview:imageView];

UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapGesture:)];
[imageView addGestureRecognizer:tap];

}

- (void)tapGesture:(UITapGestureRecognizer *)gesture {

NSString *bundlePath = [[NSBundle mainBundle] pathForResource:@"Source.bundle" ofType:nil];
NSBundle *bundle = [NSBundle bundleWithPath:bundlePath];

NSString *filePath = [bundle pathForResource:@"info.plist" ofType:nil];
NSArray  *dataArr = [NSArray arrayWithContentsOfFile:filePath];

NSDictionary *dict = dataArr[0];

NSString *gifPath = [bundle pathForResource:dict[@"gif"] ofType:nil];
NSURL *url = [NSURL fileURLWithPath:gifPath];
GifView *gifView = [[GifView alloc] initWithCenter:CGPointMake(150, 150) fileURL:url];
self.gifView = gifView;
[self.view addSubview:gifView];

[self.gifView startGif];

}

@end

.h文件

#import <UIKit/UIKit.h>

@interface GifView : UIView

/*
* @brief desingated initializer
*/
- (id)initWithCenter:(CGPoint)center fileURL:(NSURL*)fileURL;

/*
* @brief start Gif Animation
*/
- (void)startGif;

/*
* @brief stop Gif Animation
*/
- (void)stopGif;

/*
* @brief get frames image(CGImageRef) in Gif
*/
+ (NSArray*)framesInGif:(NSURL*)fileURL;

@end

.m文件

#import "GifView.h"
#import <ImageIO/ImageIO.h>
#import <QuartzCore/CoreAnimation.h>

/*
* @brief resolving gif information
*/
void getFrameInfo(CFURLRef url, NSMutableArray *frames, NSMutableArray *delayTimes, CGFloat *totalTime,CGFloat *gifWidth, CGFloat *gifHeight)
{
// 读取图片数据
CGImageSourceRef gifSource = CGImageSourceCreateWithURL(url, NULL);

// get frame count 获取图片数量
size_t frameCount = CGImageSourceGetCount(gifSource);

for (size_t i = 0; i < frameCount; ++i) {
// get each frame 获取图片大小
CGImageRef frame = CGImageSourceCreateImageAtIndex(gifSource, i, NULL);
[frames addObject:(__bridge id)frame];
CGImageRelease(frame);

// get gif info with each frame 获取图片信息
NSDictionary *dict = (NSDictionary*)CFBridgingRelease(CGImageSourceCopyPropertiesAtIndex(gifSource, i, NULL));
NSLog(@"kCGImagePropertyGIFDictionary %@", [dict valueForKey:(NSString*)kCGImagePropertyGIFDictionary]);

// get gif size
if (gifWidth != NULL && gifHeight != NULL) {
*gifWidth = [[dict valueForKey:(NSString*)kCGImagePropertyPixelWidth] floatValue];
*gifHeight = [[dict valueForKey:(NSString*)kCGImagePropertyPixelHeight] floatValue];
}

// kCGImagePropertyGIFDictionary中kCGImagePropertyGIFDelayTime，kCGImagePropertyGIFUnclampedDelayTime值是一样的
NSDictionary *gifDict = [dict valueForKey:(NSString*)kCGImagePropertyGIFDictionary];
[delayTimes addObject:[gifDict valueForKey:(NSString*)kCGImagePropertyGIFDelayTime]];

if (totalTime) {
*totalTime = *totalTime + [[gifDict valueForKey:(NSString*)kCGImagePropertyGIFDelayTime] floatValue];
}
}
}

@interface GifView () {

NSMutableArray *_frames;
NSMutableArray *_frameDelayTimes;

CGFloat _totalTime;         // seconds
CGFloat _width;
CGFloat _height;
}

@end

@implementation GifView

- (id)initWithCenter:(CGPoint)center fileURL:(NSURL*)fileURL;
{
self = [super initWithFrame:CGRectZero];
if (self) {

self.backgroundColor = [UIColor clearColor];

_frames = [[NSMutableArray alloc] init];
_frameDelayTimes = [[NSMutableArray alloc] init];

_width = 0;
_height = 0;

if (fileURL) {
getFrameInfo((__bridge CFURLRef)fileURL, _frames, _frameDelayTimes, &_totalTime, &_width, &_height);
}

self.frame = CGRectMake(0, 0, _width, _height);
self.center = center;
}

return self;
}

+ (NSArray*)framesInGif:(NSURL *)fileURL
{
NSMutableArray *frames = [NSMutableArray arrayWithCapacity:3];
NSMutableArray *delays = [NSMutableArray arrayWithCapacity:3];

getFrameInfo((__bridge CFURLRef)fileURL, frames, delays, NULL, NULL, NULL);

return frames;
}

- (void)startGif
{
CAKeyframeAnimation *animation = [CAKeyframeAnimation animationWithKeyPath:@"contents"];

NSMutableArray *times = [NSMutableArray arrayWithCapacity:3];
CGFloat currentTime = 0;
int count = (int)_frameDelayTimes.count;
for (int i = 0; i < count; ++i) {
[times addObject:[NSNumber numberWithFloat:(currentTime / _totalTime)]];
currentTime += [[_frameDelayTimes objectAtIndex:i] floatValue];
}
[animation setKeyTimes:times];

NSMutableArray *images = [NSMutableArray arrayWithCapacity:3];
for (int i = 0; i < count; ++i) {
[images addObject:[_frames objectAtIndex:i]];
}

[animation setValues:images];
[animation setTimingFunction:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear]];
animation.duration = _totalTime;
animation.delegate = self;
animation.repeatCount = 1;

[self.layer addAnimation:animation forKey:@"gifAnimation"];

dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(_totalTime * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
[self stopGif];
});
}

- (void)stopGif
{
[self.layer removeAllAnimations];

[self removeFromSuperview];
}

// remove contents when animation end
- (void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag
{
self.layer.contents = nil;
}