您的位置：首页 > 移动开发 > IOS开发

iOS异步加载缓存图片

2015-10-08 18:50 405 查看

- (void)viewDidLoad {
[super
viewDidLoad];
imageView = [[UIImageView
alloc] init];
[imageView
setBackgroundColor:[UIColor
grayColor]];
imageView.frame =
CGRectMake(60,
60, 200,
200);
[self.view
addSubview:imageView];
NSOperationQueue *operationQueue = [[NSOperationQueue
alloc] init];
NSInvocationOperation *op = [[NSInvocationOperation
alloc] initWithTarget:self
selector:@selector(downloadImage)
object:nil];
[operationQueue
addOperation:op];
}

- (void)downloadImage {
NSArray *paths =
NSSearchPathForDirectoriesInDomains(NSCachesDirectory,
NSUserDomainMask, YES);
NSString *diskCachePath = [[paths
objectAtIndex:0]
stringByAppendingPathComponent:@"imageCache"];
//如果目录imageCache不存在，创建目录
if (![[NSFileManager
defaultManager] fileExistsAtPath:diskCachePath]) {

NSError *error=nil;
[[NSFileManager
defaultManager] createDirectoryAtPath:diskCachePath
withIntermediateDirectories:YES
attributes:nil
error:&error];
}
NSString *localPath = [NSString
stringWithFormat:@"%@/headimage.png",diskCachePath];

//如果有缓存图片，直接读取cache内的缓存图片
if ([[NSFileManager
defaultManager] fileExistsAtPath:localPath]) {

NSData *data = [NSData
dataWithContentsOfFile:localPath];

dispatch_async(dispatch_get_main_queue(), ^{

imageView.image = [UIImage
imageWithData:data];
});
}
else{

NSURL *imagePathUrl = [NSURL
URLWithString:@"http://s15.sinaimg.cn/middle/9914f9fdhbc6170891ebe&690.png"];

NSData *data = [NSData
dataWithContentsOfURL:imagePathUrl];

dispatch_async(dispatch_get_main_queue(), ^{

imageView.image = [UIImage
imageWithData:data];
});
[data
writeToFile:localPath atomically:YES];
}
}

内容来自用户分享和网络整理，不保证内容的准确性，如有侵权内容，可联系管理员处理

标签：

相关文章推荐

新的分享

章节导航