适配的时候根据屏幕尺寸判断机型

/**
 *  是否是iPhone4/4s
 */

#define iPhone4/4s  ([UIScreen instancesRespondToSelector:@selector(currentMode)] ? CGSizeEqualToSize(CGSizeMake(640,960),[[UIScreen mainScreen] currentMode].size) : NO)

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


/**
 *  是否是iPhone6
 */
#define iPhone6 ([UIScreen instancesRespondToSelector:@selector(currentMode)] ? CGSizeEqualToSize(CGSizeMake(750, 1334), [[UIScreen mainScreen] currentMode].size) : NO)


/**
 *  是否是iPhone6Plus
 */
#define iPhone6Plus ([UIScreen instancesRespondToSelector:@selector(currentMode)] ? CGSizeEqualToSize(CGSizeMake(1242, 2208), [[UIScreen mainScreen] currentMode].size) : NO)

if (iPhone4/4s){

//在4或者4s上要做的事情

}