获取iOS设备信息

由于最近要做iPhone6和iPhone6+的适配工作，所以难免会需要对设备型号进行判断，就借此机会总结下判断设备的方法

1.根据屏幕宽度大小进行判断

#define iPhone6    ([UIScreen instancesRespondToSelector:@selector( currentMode )] ? CGSizeEqualToSize(CGSizeMake(750, 1334), [[UIScreen mainScreen] currentMode].size) : NO)
#define iPhone6Plus    ([UIScreen instancesRespondToSelector:@selector( currentMode )] ? CGSizeEqualToSize(CGSizeMake(1242, 2208), [[UIScreen mainScreen] currentMode].size) : NO)

2.读取设备信息进行判断

#import "sys/utsname.h"

- (NSString *)deviceModel
{
    struct utsname systemInfo;
    uname(&systemInfo);
    return [NSString stringWithCString:systemInfo.machine
                               encoding:NSUTF8StringEncoding];
}

3.简单的读取设备model

[UIDevice currentDevice].model;

其中第三种方法是调用上层API，比较推荐使用。如果需要比较详细的设备制式信息，推荐第二种方法，关于对照表如下：

@"i386"      :@"Simulator",
@"iPod1,1"   :@"iPod Touch",      // (Original)
@"iPod2,1"   :@"iPod Touch",      // (Second Generation)
@"iPod3,1"   :@"iPod Touch",      // (Third Generation)
@"iPod4,1"   :@"iPod Touch",      // (Fourth Generation)
@"iPhone1,1" :@"iPhone",          // (Original)
@"iPhone1,2" :@"iPhone",          // (3G)
@"iPhone2,1" :@"iPhone",          // (3GS)
@"iPad1,1"   :@"iPad",            // (Original)
@"iPad2,1"   :@"iPad 2",          //
@"iPad3,1"   :@"iPad",            // (3rd Generation)
@"iPhone3,1" :@"iPhone 4",        //
@"iPhone4,1" :@"iPhone 4S",       //
@"iPhone5,1" :@"iPhone 5",        // (model A1428, AT&T/Canada)
@"iPhone5,2" :@"iPhone 5",        // (model A1429, everything else)
@"iPad3,4"   :@"iPad",            // (4th Generation)
@"iPad2,5"   :@"iPad Mini",       // (Original)
@"iPhone5,3" :@"iPhone 5c",       // (model A1456, A1532 | GSM)
@"iPhone5,4" :@"iPhone 5c",       // (model A1507, A1516, A1526 (China), A1529 | Global)
@"iPhone6,1" :@"iPhone 5s",       // (model A1433, A1533 | GSM)
@"iPhone6,2" :@"iPhone 5s",       // (model A1457, A1518, A1528 (China), A1530 | Global)
@"iPad4,1"   :@"iPad Air",        // 5th Generation iPad (iPad Air) - Wifi
@"iPad4,2"   :@"iPad Air",        // 5th Generation iPad (iPad Air) - Cellular
@"iPad4,4"   :@"iPad Mini",       // (2nd Generation iPad Mini - Wifi)
@"iPad4,5"   :@"iPad Mini"        // (2nd Generation iPad Mini - Cellular)