如 [__NSArrayM insertObject:atIndex:]: 這種只會顯示在main 怎麼找出問題點 http://stackoverflow.com/questions/13929518/nsarraym-insertobjectatindex-object-cannot-be-nil-how-determine-where-i 1) goTo the breakpoint tab in Xcode. 2) click on the '+" button at the bottom. 3) Add Exception Breakpoint a) In the break tab select both: i ) on Throw ii ) on Catch and build and r un. 4) These breakpoints will give you exactly where your app is crashing 90% of the times.