1. iOS开发过程中遇到的问题

iOS开发过程中遇到的问题

1.1. Q1:Category中重写dealloc导致通知、KVO未注销

Category如果要重写方法，必须用runtime修改该方法。
建议不要在Category中重写dealloc,应该扩展出一个释放资源的方法。在ARC中，dealloc的时候不能调[super dealloc],但是会调用[super dealloc]。

1.2. Q2:Assertion failure in -[UITableView layoutSublayersOfLayer:]

http://stackoverflow.com/questions/31340603/assertion-failure-in-uitableview-layoutsublayersoflayer-on-ios-7

iOS7的tableView的子View不能设置约束。

1.3. Q3: UIScrollView中添加UITableView，viewWidthUpdated无限循环。

UITableView宽度、高度不能对UIScrollView做约束。

1.4. Q4

1.4.1. question

构建新的 App 和 App 更新时，必须使用公共（GM）版 Xcode 6 或更高版本、OS X 以及 iOS SDK。请勿提交使用 Beta 版软件，包括 Beta 版 OS X 构建的 App。

环境：

Xcode: 7.3.1 OS X: 10.11.5 (15F34)

1.4.2. answer

用 Xcode 7.3 打包

Product > Archive > 右键 > Show in Finder > 显示包内容 > Products /Applications /xxx.app /Info.plist BuildMachineOSBuild 修改为 15D21

1.4.3. reference

http://blog.csdn.net/minjing_lin/article/details/51085361

1.5. Q5: 浮点数精度问题

question

NSString *str = @"37.3336";
float f = [str floatValue]; // f = 37.3335991

NSJSONSerialization 转 NSDictionary float 出错

answer

NSString *str = @"37.3336";
float f = [str doubleValue]; // f = 37.3336

explain

因为float类型无法精准保存, 系统会选一个接近的值来代替.而double类型则可以有更好的精度,但还是会出现类似问题。更精确的方式是使用 NSDecimalNumber

NSJSONSerialization 的问题只能服务器返回字符串

http://stackoverflow.com/questions/9328260/converting-nsstring-to-float-adds-in-decimal-places

Your issue seems to be that you don't understand how floats are stored in memory and don't know that floats aren't precise.

Exact values often can't be stored and so the system picks the closest number it can to represent it. If you look carefully, you can see that each of the outputted numbers is very close to your inputted values.

For better accuracy, try using double instead. Double does encounter the same problems, but with better precision. Floats have about 6 significant digits; doubles have more than twice that.Source

Here are some other StackOverflow answers and external articles you should read:

1.6. Q6: View 获取他的 viewController

- (UIViewController *)reactViewController
{
  id responder = [self nextResponder];
  while (responder) {
    if ([responder isKindOfClass:[UIViewController class]]) {
      return responder;
    }
    responder = [responder nextResponder];
  }
  return nil;
}

参考：

获取当前viewcontroller响应事件传递

iOS开发过程中遇到的问题