今天遇到了一个问题，本来json中返回的是Double类型，值为9.87，显示到Label 却是9.86999999999999
为了方便大家理解，我先做了如下演示
NSNumber *amount = [NSNumber numberWithDouble:9.87];
NSLog(@"normal amount %@", amount);
NSNumber *amount1 = [NSNumber numberWithDouble:3.87];
NSLog(@"normal amount1 %@", amount1);
打印的值为
Test[8924:1150018] normal amount 9.869999999999999
Test[8924:1150018] normal amount1 3.87
有问题，就要开始解决，经过一番查找，找到了以下解决办法
//1
//该方法中会规定小数点的位数
NSString *amountString1 = [NSString stringWithFormat:@"%.2f",[amount doubleValue]];
NSLog(@"amountString1 %@",amountString1);
//2
double amountDouble = [amount doubleValue];
NSString *amountDoubleStr = [NSString stringWithFormat:@"%lf", amountDouble];
NSDecimalNumber *amountNum = [NSDecimalNumber decimalNumberWithString:amountDoubleStr];
NSString *amountStr = [amountNum stringValue];
NSLog(@"amountStr %@", amountStr);
打印的值为
Test[9451:1317790] amountStr 9.87
//3
//该方法中会规定小数点的位数
NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
formatter.maximumFractionDigits = 2;
NSString *amountString = [formatter stringFromNumber:amount];
NSLog(@"amountString %@",amountString);
打印的值为
Test[9451:1317790] amountString 9.87
//4
NSNumberFormatter *formatter2 = [[NSNumberFormatter alloc] init];
formatter2.numberStyle = NSNumberFormatterDecimalStyle;
//去掉千位分隔符，举例123,456.88加了这句会变成123456.88
[formatter2 setGroupingSeparator:@""];
//formatter2.maximumFractionDigits 默认值是3
NSString *amountString2 = [formatter2 stringFromNumber:amount];
NSLog(@"amountString2 %@",amountString2);
打印的值为
Test[9451:1317790] amountString2 9.87
//建议添加category
//.h
@interface NSNumber (Cd)
- (NSString *)LGDoubleStringValue;
- (NSString *)LGDoubleStringValueWithDigits:(NSUInteger)digits;
@end
//.m
@implementation NSNumber (Cd)
- (NSString *)LGDoubleStringValue
{
return [self LGDoubleStringValueWithDigits:2];
}
- (NSString *)LGDoubleStringValueWithDigits:(NSUInteger)digits
{
NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
formatter.numberStyle = NSNumberFormatterDecimalStyle;
formatter.maximumFractionDigits = digits;
[formatter setGroupingSeparator:@""];
NSString *retString = [formatter stringFromNumber:self];
return retString;
}
@end
//使用方法
NSLog(@"%@",@(9.8712132123));
NSLog(@"%@",[@(9.87123131) LGDoubleStringValue]);
NSLog(@"%@",[@(9.871231313) LGDoubleStringValueWithDigits:5]);
//输出结果为
Test[10318:1500287] 9.871213212300001
Test[10318:1500287] 9.87
Test[10318:1500287] 9.87123
参考以下网址
出现问题的原因 https://www.aliyun.com/jiaocheng/400490.html
https://stackoverflow.com/questions/24246565/objective-c-double-to-nsstring-with-x-many-decimals
NSNumberFormatter属性
