Develop app-compatible iOS7 on Xcode 6.x

Apps that are developed on Xcode 6.x may appear:

"Unable to create description in Descriptionforlayoutattribute_layoutitem_coefficient. Something is nil "

Because the lazy use of reset to suggested constraints, AutoLayout help me automatically added baseline constraints, and baseline only iOS8 later, compatible IOS7 collapsed, Directly remove baseline related constraint.

1, Baseline

• crash info:
  

• because of the lazy use of reset to suggested Constraints, AutoLayout help me automatically add baseline constraints, and baseline only iOS8 later only, compatible iOS7 crash, directly remove baseline related constraint can.

• reference link
  http:// stackoverflow.com/questions/26024906/ unable-to-create-description-in-descriptionforlayoutattribute-layoutitem-coeffi/26045383#26045383

2, [[Uinavigationbar appearance] settranslucent:no]

• crash info

   *** terminating app Due to uncaught exception ' nsinvalidargumentexception ', Reason: ' * * * illegal property type, C for appearance setter, _inst Allappearanceswizzlesforsetter: ' 
    

• cause
  iOS8.0 after [ Uinavigationbar appearance] can settranslucent, compatible iOS7 need to add judgment

   if (IOS8 _or_later && [Uinavigationbar conformstoprotocol: @protocol (Uiappearancecontainer)]) {
        [[uinavigationbar appearance] settranslucent:no]; 
    } 
    

• reference links
  http ://stackoverflow.com/questions/19125468/why-does-uinavigationbar-appearance-settranslucentno-crash-my-app

3. Storyboard Segue Show

• Abnormal phenomena

  
  

  SB. Segue Use Show

  
  

  It's normal push under the iOS8.

IOS7 to be launched from the bottom, and no navigation

• Reason
  Under IOS7, if you do not set Navigationcontroller to Initcontroller,show, the push is automatically converted to modal. In short, the segue of every show in SB must ensure that its initial position has a navigationcontroller.

• Reference links
  Http://stackoverflow.com/questions/25633739/could-not-instantiate-class-named-uistoryboardshowseguetemplate-how-can-i-ma

4, constrain to margin

• Abnormal phenomena

  
  

  Abnormal whitespace appears at the top of the TableView

• Reason
  This is set up the relationship between constrain to margins, this thing is also iOS8 after, the hook removed, OK

Develop app-compatible iOS7 on Xcode 6.x