IOS通过URL下载保存图片

-(void) downLoadImageFromURL:(NSString *)fileURL withName:(NSString *)imageName
{
//Check Image Is Exists
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString * filePath = [DOCUMENT_PATH stringByAppendingPathComponent:imageName];
filePath = [NSString stringWithFormat:@"%@.jpg", filePath];
if ([fileManager fileExistsAtPath:filePath])
{
return ;
}

//Get Image From URL
UIImage * imageFromURL = [self getImageFromURL:fileURL];

//Save Image to Directory
[self saveImage:imageFromURL withFileName:imageName ofType:@"jpg" inDirectory:DOCUMENT_PATH];

//Get Document Path All Files
NSArray *file = [[[NSFileManager alloc] init] subpathsAtPath:DOCUMENT_PATH];
NSLog(@"%@",file);
}

-(UIImage *) getImageFromURL:(NSString *)fileURL
{
NSData * data = [NSData dataWithContentsOfURL:[NSURL URLWithString:fileURL]];
return [UIImage imageWithData:data];
}

-(void) saveImage:(UIImage *)image withFileName:(NSString *)imageName ofType:(NSString *)extension inDirectory:(NSString *)directoryPath
{
if ([[extension lowercaseString] isEqualToString:@"png"])
{
[UIImagePNGRepresentation(image) writeToFile:[directoryPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.%@", imageName, @"png"]] options:NSAtomicWrite error:nil];
}
else if ([[extension lowercaseString] isEqualToString:@"jpg"] || [[extension lowercaseString] isEqualToString:@"jpeg"])
{
[UIImageJPEGRepresentation(image, 1.0) writeToFile:[directoryPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.%@", imageName, @"jpg"]] options:NSAtomicWrite error:nil];
}
else
{
NSLog(@"文件后缀不认识");
}
}

NSString * imageURL = @"http://img.sccnn.com/bimg/337/49760.jpg";
[self downLoadImageFromURL:imageURL withName:@"image"];