绝对值/类/成员

//绝对值

float count = 1.2;

//NSLog(@"===%.9f",count);//1.200000048

//fabs(count-1.2)求的是绝对值

if(fabs(count-1.2) < 0.000001) {

//在范围之内如果条件成立说明是1.2

//NSLog(@" =%.9f",count);

}

UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];

//可以是当前类，可以是父类

if([btn isKindOfClass:[UIView class]]) {

NSLog(@"is class");

} else {

NSLog(@"no class");

}

//判断是否是当前类，只能是当前类

if([btn isMemberOfClass:[UIView class]]) {

NSLog(@"is menber");

} else {

NSLog(@"no menber");

}