1、将数字转化为字符串的快捷方式

2、请彻底抛弃float类型，使用CGFloat或double，float不够精确.

BOOL b1 = YES;    BOOL b2 = NO;    NSInteger t1 = 100000;    int t2 = 200000;    float t3 = 300000.02;    CGFloat t33 = 300000.02;    double t4 = 400000.0000003;    NSNumber *num1 = @(123);    NSNumber *num2 = @(123.00005);        NSLog(@"BOOL b1:%@",[@(b1) stringValue]);           //BOOL b1:1    NSLog(@"BOOL b2:%@",[@(b2) stringValue]);           // BOOL b2:0    NSLog(@"NSInteger t1:%@",[@(t1) stringValue]);      //NSInteger t1:100000    NSLog(@"int t2:%@",[@(t2) stringValue]);            //int t2:200000    NSLog(@"float t3:%@",[@(t3) stringValue]);          //float t3:300000            ##失真    NSLog(@"float t3:%f",t3);                           //float t3:300000.031250     ##失真　　    NSLog(@"float t3:%.2f",t3);                         //float t3:300000.03         ##失真    NSLog(@"float t33:%@",[@(t33) stringValue]);        //float t33:300000.02    NSLog(@"float t33:%f",t33);                         //float t33:300000.020000    NSLog(@"double t4:%@",[@(t4) stringValue]);         //double t4:400000.0000003    NSLog(@"NSNumber *num1:%@",[num1 stringValue]);     //NSNumber *num1:123    NSLog(@"NSNumber *num2:%@",[num2 stringValue]);     //NSNumber *num2:123.00005