关于精度处理

有时会遇到价格类似精度的问题，尤其是float相减时遇到的差距，处理方案：转为NSDecimalNumber类型

//最终的真实价格

NSString * finalResult = [NSString stringWithFormat:@"%f",[self getOriginalAmount:self.finalResultArr]];

NSDecimalNumber *finalNumber = [NSDecimalNumber decimalNumberWithString:finalResult];

//售价

NSString * saleStr = [NSString stringWithFormat:@"%f",self.saleAmount];

NSDecimalNumber *saleNumber = [NSDecimalNumber decimalNumberWithString:saleStr];

//计算差价

 NSDecimalNumber*cha = [finalNumber  decimalNumberBySubtracting:saleNumber];

filat chafloat = [NSString stringWithFormat:@"特价折扣优惠 %.2f元",cha.floatValue];