如何判断当前iOS设备

1.在程序中涉及到全屏的宽高的时候，初始化的时候，代码中不要写320和480

#define Screen_height   [[UIScreen mainScreen] bounds].size.height 
#define Screen_width    [[UIScreen mainScreen] bounds].size.width   

2.使用宏定义方法判断

 #define iPhone5 ([UIScreen instancesRespondToSelector:@selector(currentMode)] ? CGSizeEqualToSize(CGSizeMake(640, 1136), [[UIScreen mainScreen] currentMode].size) : NO) 
if（iPhone5）{ 
    /*代码操作*/ 
}else{ 
    /*代码操作*/ 
} 
if([ [ UIDevice currentDevice ] userInterfaceIdiom ] == UIUserInterfaceIdiomPhone ){ 
    //IPhone设备 
}else{ 
    //ipad设备 
}  

网上还有一种方法：

+ (NSString*)deviceString  
        {  
            // 需要#import "sys/utsname.h"  
            struct utsname systemInfo;  
            uname(&systemInfo);  
            NSString *deviceString = [NSString stringWithCString:systemInfo.machine encoding:NSUTF8StringEncoding];                  
            if ([deviceString isEqualToString:@"iPhone1,1"])    return @"iPhone 1G";  
            if ([deviceString isEqualToString:@"iPhone1,2"])    return @"iPhone 3G";  
            if ([deviceString isEqualToString:@"iPhone2,1"])    return @"iPhone 3GS";  
            if ([deviceString isEqualToString:@"iPhone3,1"])    return @"iPhone 4";  
            if ([deviceString isEqualToString:@"iPhone4,1"])    return @"iPhone 4S";  
            if ([deviceString isEqualToString:@"iPhone5,2"])    return @"iPhone 5";  
            if ([deviceString isEqualToString:@"iPhone3,2"])    return @"Verizon iPhone 4";  
            if ([deviceString isEqualToString:@"iPod1,1"])      return @"iPod Touch 1G";  
            if ([deviceString isEqualToString:@"iPod2,1"])      return @"iPod Touch 2G";  
            if ([deviceString isEqualToString:@"iPod3,1"])      return @"iPod Touch 3G";  
            if ([deviceString isEqualToString:@"iPod4,1"])      return @"iPod Touch 4G";  
            if ([deviceString isEqualToString:@"iPad1,1"])      return @"iPad";  
            if ([deviceString isEqualToString:@"iPad2,1"])      return @"iPad 2 (WiFi)";  
            if ([deviceString isEqualToString:@"iPad2,2"])      return @"iPad 2 (GSM)";  
            if ([deviceString isEqualToString:@"iPad2,3"])      return @"iPad 2 (CDMA)";  
            if ([deviceString isEqualToString:@"i386"])         return @"Simulator";  
            if ([deviceString isEqualToString:@"x86_64"])       return @"Simulator";  
            NSLog(@"NOTE: Unknown device type: %@", deviceString);  
            return deviceString;  
        }