title: UITableView contentInset changes
body: <p>I have set the contentInset of the tableView in the method<code>- (void)viewDidLoad</code> and the property is<code>self.tableView.contentInset = UIEdgeInsetsMake(200, 0, 200, 0);</code>
  however ,<code>tableView.contentInset</code>  will be changed automaticly to :<code>{64, 0, 0, 0}
  </code>.Why this happened, and how can I slove this problem?</p>
  
  <p>Environment: XCode8.1 iOS10.1</p>
  
  <pre><code>    #import "YAVideoViewController.h"
  static NSString * const ID = @"cell";
  @interface YAVideoViewController ()
  
  @end
  
  @implementation YAVideoViewController
  
  - (void)viewDidLoad {
      [super viewDidLoad];
  
  
  
      self.view.backgroundColor = [UIColor arcColor];
      [self.tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:ID];
  
      self.tableView.contentInset = UIEdgeInsetsMake(200, 0, 200, 0);
  }
  
  
  
  - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
  
      return 50;
  }
  
  
  
  - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
      UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:ID forIndexPath:indexPath];
  
      cell.textLabel.text = [NSString stringWithFormat:@"第%ld个cell",indexPath.row];
  
      return cell;
  }
  
  @end
  </code></pre>