判断 iPhone5的

define iPhone5 ([UIScreen instancesRespondToSelector:@selector(currentMode)] ? CGSizeEqualToSize(CGSizeMake(640, 1136), [[UIScreen mainScreen] currentMode].size) : NO)

iPhone6和iPhone7有放大模式，开启放大模式后，手机分辨率会发生变化，iPhone6的会变成iPhone5的分辨率，如果进行屏幕适配，可以按照iPhone5的屏幕适配放大模式的iPhone6.

define iPhone6 ([UIScreen instancesRespondToSelector:@selector(currentMode)] ? (CGSizeEqualToSize(CGSizeMake(750, 1334), [[UIScreen mainScreen] currentMode].size) || CGSizeEqualToSize(CGSizeMake(640, 1136), [[UIScreen mainScreen] currentMode].size)) : NO)

iPhone6P和iPhone7P，开启放大模式后，分辨率不会降到iPhone6的大小，所以可以单独适配

define iPhone6plus ([UIScreen instancesRespondToSelector:@selector(currentMode)] ? (CGSizeEqualToSize(CGSizeMake(1125, 2001), [[UIScreen mainScreen] currentMode].size) || CGSizeEqualToSize(CGSizeMake(1242, 2208), [[UIScreen mainScreen] currentMode].size)) : NO)