NSNumber

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];