機型iPad mini:
橫屏:[UIScreen mainScreen].bounds.size(1024,768)
iOS8.3橫屏screen:width=1024.000000,height=768.000000
iOS7.1:橫屏screen:width=768.000000,height=1024.000000
豎屏:[UIScreen mainScreen].bounds.size(768,1024)
iOS8.3豎屏screen:width=768.000000,height=1024.000000
iOS7.1:豎屏screen:width=768.000000,height=1024.000000
適配時判斷設備方向時用
[[UIApplication sharedApplication] statusBarOrientation],該方法當設備水平放於桌面時也能準確