28
有一个简单的办法做这样的事情..ObjC /可可类将大小转换为可读的字符串？
[NSMagicDataConverter humanStringWithBytes:20000000]
..这将返回“19.1MB”？
A
回答
18
这是我自己取的问题：
enum {
kUnitStringBinaryUnits = 1 << 0,
kUnitStringOSNativeUnits = 1 << 1,
kUnitStringLocalizedFormat = 1 << 2
};
NSString* unitStringFromBytes(double bytes, uint8_t flags){
static const char units[] = { '\0', 'k', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y' };
static int maxUnits = sizeof units - 1;
int multiplier = (flags & kUnitStringOSNativeUnits && !leopardOrGreater() || flags & kUnitStringBinaryUnits) ? 1024 : 1000;
int exponent = 0;
while (bytes >= multiplier && exponent < maxUnits) {
bytes /= multiplier;
exponent++;
}
NSNumberFormatter* formatter = [[[NSNumberFormatter alloc] init] autorelease];
[formatter setMaximumFractionDigits:2];
if (flags & kUnitStringLocalizedFormat) {
[formatter setNumberStyle: NSNumberFormatterDecimalStyle];
}
// Beware of reusing this format string. -[NSString stringWithFormat] ignores \0, *printf does not.
return [NSString stringWithFormat:@"%@ %cB", [formatter stringFromNumber: [NSNumber numberWithDouble: bytes]], units[exponent]];
}
默认情况下（如果0传递为flags），它会输出SI单位（基地10次）。您可以设置kUnitStringBinaryUnits选择适合内存的二进制（基本两个）单位，或者kUnitStringOSNativeUnits根据操作系统版本自动选择单位类型（预先Leopard获得基数为2，后Leopard获得基数为10）。设置kUnitStringLocalizedFormat根据用户当前的语言环境设置字符串的格式。例如：
unitStringFromBytes(1073741824, 0); // → "1.07 GB"
unitStringFromBytes(1073741824, kUnitStringBinaryUnits); // → "1 GB"
unitStringFromBytes(1073741824, kUnitStringOSNativeUnits | kUnitStringLocalizedFormat); // → "1.07 GB" (In Mac OS 10.6)
unitStringFromBytes(123456789, kUnitStringOSNativeUnits | kUnitStringLocalizedFormat); // → "12,345.68 YB" (In Mac OS 10.6, in the US)
unitStringFromBytes(123456789, kUnitStringOSNativeUnits | kUnitStringLocalizedFormat); // → "12.345,68 YB" (In Mac OS 10.6, in Spain)
下面是OS本地单元所需的辅助函数：
BOOL leopardOrGreater(){
static BOOL alreadyComputedOS = NO;
static BOOL leopardOrGreater = NO;
if (!alreadyComputedOS) {
SInt32 majorVersion, minorVersion;
Gestalt(gestaltSystemVersionMajor, &majorVersion);
Gestalt(gestaltSystemVersionMinor, &minorVersion);
leopardOrGreater = ((majorVersion == 10 && minorVersion >= 5) || majorVersion > 10);
alreadyComputedOS = YES;
}
return leopardOrGreater;
}
5
NSString *stringFromFileSize(NSInteger theSize)
{
/*
From http://snippets.dzone.com/posts/show/3038 with slight modification
*/
float floatSize = theSize;
if (theSize<1023)
return([NSString stringWithFormat:@"%i bytes",theSize]);
floatSize = floatSize/1024;
if (floatSize<1023)
return([NSString stringWithFormat:@"%1.1f KB",floatSize]);
floatSize = floatSize/1024;
if (floatSize<1023)
return([NSString stringWithFormat:@"%1.1f MB",floatSize]);
floatSize = floatSize/1024;
return([NSString stringWithFormat:@"%1.1f GB",floatSize]);
}
22
我会玉米粥到NSFormatter子类此。
#import <Foundation/Foundation.h>
@interface SOFileSizeFormatter : NSNumberFormatter
{
@private
BOOL useBaseTenUnits;
}
/** Flag signaling whether to calculate file size in binary units (1024) or base ten units (1000). Default is binary units. */
@property (nonatomic, readwrite, assign, getter=isUsingBaseTenUnits) BOOL useBaseTenUnits;
@end
static const char sUnits[] = { '\0', 'K', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y' };
static int sMaxUnits = sizeof sUnits - 1;
@implementation SOFileSizeFormatter
@synthesize useBaseTenUnits;
- (NSString *) stringFromNumber:(NSNumber *)number
{
int multiplier = useBaseTenUnits ? 1000 : 1024;
int exponent = 0;
double bytes = [number doubleValue];
while ((bytes >= multiplier) && (exponent < sMaxUnits)) {
bytes /= multiplier;
exponent++;
}
return [NSString stringWithFormat:@"%@ %cB", [super stringFromNumber: [NSNumber numberWithDouble: bytes]], sUnits[exponent]];
}
@end
用法：
NSString *path = ...; // path to a file of 1,500,000 bytes
NSString *sizeString = nil;
NSNumber *sizeAttrib = [[[NSFileManager defaultManager] attributesOfItemAtPath:path error:NULL]objectForKey:NSFileSize];
SOFileSizeFormatter *sizeFormatter = [[[SOFileSizeFormatter alloc] init] autorelease];
[sizeFormatter setMaximumFractionDigits:2];
sizeString = [sizeFormatter stringFromNumber:sizeAttrib];
// sizeString ==> @"1.43 MB"
[sizeFormatter setUseBaseTenUnits:YES];
sizeString = [sizeFormatter stringFromNumber:sizeAttrib];
// sizeString ==> @"1.5 MB"
6
这是一个比较客观的类似C的功能（使用的NSNumber，NSArray中，NSStirng等）做这种转换。
这是基于Sidnicious的回答，所以非常感谢在那里完成的最初工作。也基于维基百科的文章。
一般使用如下：[HumanReadableDataSizeHelper humanReadableSizeFromBytes:[NSNumber numberWithDouble:doubleValue]]。
但是，它看起来像你想SI单位有1024乘数，因此会使用这样的：[HumanReadableDataSizeHelper humanReadableSizeFromBytes:[NSNumber numberWithDouble:doubleValue] useSiPrefixes:YES useSiMultiplier:NO]
我默认为二进制前缀（KI，MI）的原因是因为那些似乎是最将适当的单位前缀设置为用于计算机上数据的大小。你所要求的是SI单位的前缀，但使用1024的乘数，在技术上是不正确的。虽然我会注意到，1024的倍数的SI前缀是相当常见的，并且二进制前缀不被很好接受（根据维基百科）。
HumanReadableDataSizeHelper.h
@interface HumanReadableDataSizeHelper : NSObject
/**
@brief Produces a string containing the largest appropriate units and the new fractional value.
@param sizeInBytes The value to convert in bytes.
This function converts the bytes value to a value in the greatest units that produces a value >= 1 and returns the new value and units as a string.
The magnitude multiplier used is 1024 and the prefixes used are the binary prefixes (ki, Mi, ...).
*/
+ (NSString *)humanReadableSizeFromBytes:(NSNumber *)sizeInBytes;
/**
@brief Produces a string containing the largest appropriate units and the new fractional value.
@param sizeInBytes The value to convert in bytes.
@param useSiPrefixes Controls what prefix-set is used.
@param useSiMultiplier Controls what magnitude multiplier is used.
This function converts the bytes value to a value in the greatest units that produces a value >= 1 and returns the new value and units as a string.
When useSiPrefixes is true, the prefixes used are the SI unit prefixes (k, M, ...).
When useSiPrefixes is false, the prefixes used are the binary prefixes (ki, Mi, ...).
When useSiMultiplier is true, the magnitude multiplier used is 1000
When useSiMultiplier is false, the magnitude multiplier used is 1024.
*/
+ (NSString *)humanReadableSizeFromBytes:(NSNumber *)sizeInBytes useSiPrefixes:(BOOL)useSiPrefixes useSiMultiplier:(BOOL)useSiMultiplier;
@end
HumanReadableDataSizeHelper.m
@implementation HumanReadableDataSizeHelper
+ (NSString *)humanReadableSizeFromBytes:(NSNumber *)sizeInBytes
{
return [self humanReadableSizeFromBytes:sizeInBytes useSiPrefixes:NO useSiMultiplier:NO];
}
+ (NSString *)humanReadableSizeFromBytes:(NSNumber *)sizeInBytes useSiPrefixes:(BOOL)useSiPrefixes useSiMultiplier:(BOOL)useSiMultiplier
{
NSString *unitSymbol = @"B";
NSInteger multiplier;
NSArray *prefixes;
if (useSiPrefixes)
{
/* SI prefixes
http://en.wikipedia.org/wiki/Kilo-
kilobyte (kB) 10^3
megabyte (MB) 10^6
gigabyte (GB) 10^9
terabyte (TB) 10^12
petabyte (PB) 10^15
exabyte (EB) 10^18
zettabyte (ZB) 10^21
yottabyte (YB) 10^24
*/
prefixes = [NSArray arrayWithObjects: @"", @"k", @"M", @"G", @"T", @"P", @"E", @"Z", @"Y", nil];
}
else
{
/* Binary prefixes
http://en.wikipedia.org/wiki/Binary_prefix
kibibyte (KiB) 2^10 = 1.024 * 10^3
mebibyte (MiB) 2^20 ≈ 1.049 * 10^6
gibibyte (GiB) 2^30 ≈ 1.074 * 10^9
tebibyte (TiB) 2^40 ≈ 1.100 * 10^12
pebibyte (PiB) 2^50 ≈ 1.126 * 10^15
exbibyte (EiB) 2^60 ≈ 1.153 * 10^18
zebibyte (ZiB) 2^70 ≈ 1.181 * 10^21
yobibyte (YiB) 2^80 ≈ 1.209 * 10^24
*/
prefixes = [NSArray arrayWithObjects: @"", @"ki", @"Mi", @"Gi", @"Ti", @"Pi", @"Ei", @"Zi", @"Yi", nil];
}
if (useSiMultiplier)
{
multiplier = 1000;
}
else
{
multiplier = 1024;
}
NSInteger exponent = 0;
double size = [sizeInBytes doubleValue];
while ((size >= multiplier) && (exponent < [prefixes count]))
{
size /= multiplier;
exponent++;
}
NSNumberFormatter* formatter = [[[NSNumberFormatter alloc] init] autorelease];
[formatter setMaximumFractionDigits:2];
[formatter setNumberStyle:NSNumberFormatterDecimalStyle]; // Uses localized number formats.
NSString *sizeInUnits = [formatter stringFromNumber:[NSNumber numberWithDouble:size]];
return [NSString stringWithFormat:@"%@ %@%@", sizeInUnits, [prefixes objectAtIndex:exponent], unitSymbol];
}
@end
98
在OS X 10.8和iOS 6开始，你可以使用NSByteCountFormatter。
你的榜样应该是这样的：
[NSByteCountFormatter stringFromByteCount:20000000 countStyle:NSByteCountFormatterCountStyleFile];
2
您可以使用FormatterKit及其TTTUnitOfInformationFormatter类：
https://github.com/mattt/FormatterKit
它也可通过与的CocoaPods：
pod 'FormatterKit', '~> 1.1.1'
1
- (id)transformedValue:(id)value
{
double convertedValue = [value doubleValue];
int multiplyFactor = 0;
NSArray *tokens = @[@"bytes",@"KB",@"MB",@"GB",@"TB"];
while (convertedValue > 1024) {
convertedValue /= 1024;
multiplyFactor++;
}
return [NSString stringWithFormat:@"%4.2f %@",convertedValue, tokens[multiplyFactor]];
}
0
我知道这个问题是对的OBJ C，但如果有人寻找一个迅速版本：
public static func fileSizeDisplay(fromBytes:Int) -> String {
let display = ["bytes","KB","MB","GB","TB","PB"]
var value:Double = Double(fromBytes)
var type = 0
while (value > 1024){
value /= 1024
type = type + 1
}
return "\(String(format:"%g", value)) \(display[type])"
}
相关问题
- 1. Java的转换字符流为人类的“可读”字符串
- 2. 如何将数据类型转换为可读的字符串
- 3. 将字符串转换为可变
- 4. 将可选字符串转换为Int64
- 5. 将二进制字符转换为人类可读的字符串？
- 6. 将字节数组转换为可读字符串
- 7. 如何将X509扩展字节转换为可读字符串？
- 8. parse5 SAXParser：管道转换为可读的流转换字符串
- 9. 如何将OctetString转换为可读的字符串（C＃）？
- 10. 将Color类中的颜色转换为人类可读的字符串
- 11. 如何字节串转换为可读的字符串
- 12. 将UTF-8编码的字符串转换为可读的字符串
- 13. 将日期字符串转换为SQL可读日期格式
- 14. 如何将字符串转换为可读流？
- 15. 将SNMP八位字符串转换为浮点（可读字符串）
- 16. jQuery的：字符串转换为可变
- 17. 字符串转换为可变的Java
- 18. 将符号转换为可读
- 19. 可可路径字符串转换
- 20. 使用Pig将人类可读的字符串日期转换为日期？
- 21. 将cron表达式转换为人类可读字符串的JavaScript API
- 22. 翻译是转换秒的人类可读的字符串
- 23. 将未知字符转换为可读字符
- 24. 是否可以将字符串转换为List数据类型？
- 25. 将字符串转换为JSON可转换阵列
- 26. TextEncoding可以转换为字符串吗？
- 27. Javascript：可以将字符串转换为/转换为类型常量吗？
- 28. 在bash中将可读的字符转换为字节
- 29. 如何将字符串转换成可读的视图
- 30. 可可按字符读取字符串？
NSByteCountFormatter在iOS 6.0以上版本以及OS X 10.8或更高版本 – 2013-06-21 18:18:18
http://stackoverflow.com/a/ 7846956/944634 – 2013-08-03 15:13:48