json解析精度问题

由于后台传过来的值是float或者double类型,解析之后作为对象放到字典或数组里面,被转成nsstring或者nsnumber会有一定的误差,很正常

解决办法,通过NSNumberFormatter，可以设置NSNumber输出的格式;

NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];

formatter.numberStyle = NSNumberFormatterDecimalStyle;

NSString *string = [formatter stringFromNumber:[NSNumber numberWithInt:123.85999999999]];

NSLog(@"Formatted number string:%@",string);

//枚举类型

typedef NS_ENUM(NSUInteger, NSNumberFormatterRoundingMode) {

NSNumberFormatterRoundCeiling = kCFNumberFormatterRoundCeiling,

NSNumberFormatterRoundFloor = kCFNumberFormatterRoundFloor,

NSNumberFormatterRoundDown = kCFNumberFormatterRoundDown,

NSNumberFormatterRoundUp = kCFNumberFormatterRoundUp,

NSNumberFormatterRoundHalfEven = kCFNumberFormatterRoundHalfEven,

NSNumberFormatterRoundHalfDown = kCFNumberFormatterRoundHalfDown,

NSNumberFormatterRoundHalfUp = kCFNumberFormatterRoundHalfUp

};

NSNumberFormatterRoundCeiling = kCFNumberFormatterRoundCeiling,//四舍五入，直接输出124

NSNumberFormatterRoundFloor = kCFNumberFormatterRoundFloor,//保留小数输出123.86

NSNumberFormatterRoundDown = kCFNumberFormatterRoundDown,//加上了人民币标志

NSNumberFormatterRoundUp = kCFNumberFormatterRoundUp,//百分号表示

NSNumberFormatterRoundHalfEven = kCFNumberFormatterRoundHalfEven

NSNumberFormatterRoundHalfDown = kCFNumberFormatterRoundHalfDown

NSNumberFormatterRoundHalfUp = kCFNumberFormatterRoundHalfUp