SDWebImage清理缓存及其使用问题

float cache = [[SDImageCache sharedImageCache] getSize] / 1024.0 / 1024.0;
NSString *clearCacheName = cache >= 1 ? [NSString stringWithFormat:@"清理缓存(%.2fM)",cache] : [NSString stringWithFormat:@"清理缓存(%.2fK)",cache * 1024];

UIAlertController *alertC = [UIAlertController alertControllerWithTitle:@"提示" message:clearCacheName preferredStyle:(UIAlertControllerStyleAlert)];

UIAlertAction *cleanAction = [UIAlertAction actionWithTitle:@"清理" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {

[[SDImageCache sharedImageCache] clearDisk];

UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"提示" message:@"缓存清理完成" delegate:self cancelButtonTitle:@"确定" otherButtonTitles:nil, nil];
[alertView show];
}];
[alertC addAction:cancelAction];
[alertC addAction:cleanAction];

[self presentViewController:alertC animated:YES completion:nil];