一、各設備屏幕尺寸
| 設備 | 對角線 | 分辨率(點\1pt=1/72英寸) | Scale Factor | 分辨率(像素\px) | PPI（DPI） |
|---|---|---|---|---|---|
| iPhone 4/4s | 3.5英寸 | 320x480 | @2x | 640x960 | 326 |
| iPhone 5/5s/5c | 4英寸 | 320x568 | @2x | 640x1136 | 326 |
| iPhone 6/7/8 | 4.7英寸 | 375x667 | @2x | 750x1334 | 326 |
| iPhone 6P/7P/8P | 5.5英寸 | 414x736 | @3x | 1242x2208(渲染后1080x1920) | 401 |
| iPhone X | 5.8英寸 | 375*812 | @3x | 1125x2436 | 458 |
注：Plus設備渲染后像素降低的原因
iPhone Plus的實際PPI是401，理論上蘋果應該用401 / 326 x @2x = @2.46x的素材，
但是這個奇葩的臂力對于開發者而言很難切圖，
所以蘋果為了方便開發者就采用了@3x的素材，然后再縮放到@2.46x的屏幕上，也就是縮放到2.46 / 3 = 83%，
實際上蘋果選取了一個接近比例的87%。這樣算下來，物理分辨率和虛擬分辨率的比率是87%，也就是1080 / 0.86 = 1242，1920 / 0.87 = 2208。
二、獲取各設備名稱
#import <sys/utsname.h>
+ (NSString*)deviceModelName
{
struct utsname systemInfo;
uname(&systemInfo);
NSString *deviceModel = [NSString stringWithCString:systemInfo.machine encoding:NSUTF8StringEncoding];
//iPhone 系列
if ([deviceModel isEqualToString:@"iPhone1,1"]) return @"iPhone 1G";
if ([deviceModel isEqualToString:@"iPhone1,2"]) return @"iPhone 3G";
if ([deviceModel isEqualToString:@"iPhone2,1"]) return @"iPhone 3GS";
if ([deviceModel isEqualToString:@"iPhone3,1"]) return @"iPhone 4";
if ([deviceModel isEqualToString:@"iPhone3,2"]) return @"Verizon iPhone 4";
if ([deviceModel isEqualToString:@"iPhone4,1"]) return @"iPhone 4S";
if ([deviceModel isEqualToString:@"iPhone5,1"]) return @"iPhone 5";
if ([deviceModel isEqualToString:@"iPhone5,2"]) return @"iPhone 5";
if ([deviceModel isEqualToString:@"iPhone5,3"]) return @"iPhone 5C";
if ([deviceModel isEqualToString:@"iPhone5,4"]) return @"iPhone 5C";
if ([deviceModel isEqualToString:@"iPhone6,1"]) return @"iPhone 5S";
if ([deviceModel isEqualToString:@"iPhone6,2"]) return @"iPhone 5S";
if ([deviceModel isEqualToString:@"iPhone7,1"]) return @"iPhone 6 Plus";
if ([deviceModel isEqualToString:@"iPhone7,2"]) return @"iPhone 6";
if ([deviceModel isEqualToString:@"iPhone8,1"]) return @"iPhone 6s";
if ([deviceModel isEqualToString:@"iPhone8,2"]) return @"iPhone 6s Plus";
if ([deviceModel isEqualToString:@"iPhone9,1"]) return @"iPhone 7 (CDMA)";
if ([deviceModel isEqualToString:@"iPhone9,3"]) return @"iPhone 7 (GSM)";
if ([deviceModel isEqualToString:@"iPhone9,2"]) return @"iPhone 7 Plus (CDMA)";
if ([deviceModel isEqualToString:@"iPhone9,4"]) return @"iPhone 7 Plus (GSM)";
if([deviceModel isEqualToString:@"iPhone10,1"]) return@"iPhone 8";
if([deviceModel isEqualToString:@"iPhone10,4"]) return@"iPhone 8";
if([deviceModel isEqualToString:@"iPhone10,2"]) return@"iPhone 8 Plus";
if([deviceModel isEqualToString:@"iPhone10,5"]) return@"iPhone 8 Plus";
if([deviceModel isEqualToString:@"iPhone10,3"]) return@"iPhone X";
if([deviceModel isEqualToString:@"iPhone10,6"]) return@"iPhone X";
//iPod 系列
if ([deviceModel isEqualToString:@"iPod1,1"]) return @"iPod Touch 1G";
if ([deviceModel isEqualToString:@"iPod2,1"]) return @"iPod Touch 2G";
if ([deviceModel isEqualToString:@"iPod3,1"]) return @"iPod Touch 3G";
if ([deviceModel isEqualToString:@"iPod4,1"]) return @"iPod Touch 4G";
if ([deviceModel isEqualToString:@"iPod5,1"]) return @"iPod Touch 5G";
//iPad 系列
if ([deviceModel isEqualToString:@"iPad1,1"]) return @"iPad";
if ([deviceModel isEqualToString:@"iPad2,1"]) return @"iPad 2 (WiFi)";
if ([deviceModel isEqualToString:@"iPad2,2"]) return @"iPad 2 (GSM)";
if ([deviceModel isEqualToString:@"iPad2,3"]) return @"iPad 2 (CDMA)";
if ([deviceModel isEqualToString:@"iPad2,4"]) return @"iPad 2 (32nm)";
if ([deviceModel isEqualToString:@"iPad2,5"]) return @"iPad mini (WiFi)";
if ([deviceModel isEqualToString:@"iPad2,6"]) return @"iPad mini (GSM)";
if ([deviceModel isEqualToString:@"iPad2,7"]) return @"iPad mini (CDMA)";
if ([deviceModel isEqualToString:@"iPad3,1"]) return @"iPad 3(WiFi)";
if ([deviceModel isEqualToString:@"iPad3,2"]) return @"iPad 3(CDMA)";
if ([deviceModel isEqualToString:@"iPad3,3"]) return @"iPad 3(4G)";
if ([deviceModel isEqualToString:@"iPad3,4"]) return @"iPad 4 (WiFi)";
if ([deviceModel isEqualToString:@"iPad3,5"]) return @"iPad 4 (4G)";
if ([deviceModel isEqualToString:@"iPad3,6"]) return @"iPad 4 (CDMA)";
if ([deviceModel isEqualToString:@"iPad4,1"]) return @"iPad Air";
if ([deviceModel isEqualToString:@"iPad4,2"]) return @"iPad Air";
if ([deviceModel isEqualToString:@"iPad4,3"]) return @"iPad Air";
if ([deviceModel isEqualToString:@"iPad5,3"]) return @"iPad Air 2";
if ([deviceModel isEqualToString:@"iPad5,4"]) return @"iPad Air 2";
if ([deviceModel isEqualToString:@"iPad4,4"] ||[deviceModel isEqualToString:@"iPad4,5"] ||[deviceModel isEqualToString:@"iPad4,6"]) return @"iPad mini 2";
if ([deviceModel isEqualToString:@"iPad4,7"] ||[deviceModel isEqualToString:@"iPad4,8"] ||[deviceModel isEqualToString:@"iPad4,9"]) return @"iPad mini 3";
if ([deviceModel isEqualToString:@"i386"]) return @"Simulator";
if ([deviceModel isEqualToString:@"x86_64"]) return @"Simulator";
return deviceModel;
}
