int a = 10;
NSNumber * i = [NSNumber numberWithInt:a]; 封装
int b = [i intValue]; 拆封
char ch = 'a';
NSNumber * ch1 = [NSNumber numberWithChar:ch];
char ch2 = [ch charValue];
double d = 3.14;
NSNumber * d1 = [NSNumber numberWithDouble:d];
double d2 = [d1 doubleValue];
float f = 6.28;
NSNumber * f1 = [NSNumber numberWithFloat:f];
float f2 = [f1 floatValue];
BOOL b = YES;
NSNumber * b1 = [NSNumber numberWithBool:b];
BOOL b2 = [b1 boolValue];
