iOS 项目优化

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
  
});

dispatch_async(dispatch_get_main_queue(), ^(void) {
          [yourTableView reloadData];
         });

//方法2     这种加载方式由于我们将它释放掉了，会再次加载。
UIImage *image2 = [UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"image.png" ofType:nil]];  
//方法3  
NSData *imageData = [NSData dataWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"image.png" ofType:nil]];  
UIImage *image3 = [UIImage imageWithData:imageData];  
UIImage  *image=[UIImage imageWithContentsOfFile:@"file://doucment/image.png"];