将int转换为缩短的格式化字符串

Question

用户将输入美元值作为int，我想将结果转换为缩短的格式化字符串。所以如果用户输入1700，字符串会说“$ 1.7k”。如果用户输入32600000，字符串将会说“$ 32.6m”。

更新

这里是我到目前为止的代码。它似乎正在为数​​字〜10K工作。我只是添加更多的if语句为更大的数字。但是，有没有更有效的方法来做到这一点？

NSNumberFormatter *nformat = [[NSNumberFormatter alloc] init]; 
[nformat setFormatterBehavior:NSNumberFormatterBehavior10_4]; 
[nformat setCurrencySymbol:@"$"]; 
[nformat setNumberStyle:NSNumberFormatterCurrencyStyle]; 
double doubleValue = 10200; 
NSString *stringValue = nil; 
NSArray *abbrevations = [NSArray arrayWithObjects:@"k", @"m", @"b", @"t", nil] ; 

for (NSString *s in abbrevations) 
{ 

    doubleValue /= 1000.0 ; 

    if (doubleValue < 1000.0) 
    { 

     if ((long long)doubleValue % (long long) 100 == 0) { 
      [nformat setMaximumFractionDigits:0]; 
     } else {     
      [nformat setMaximumFractionDigits:2]; 
     } 

     stringValue = [NSString stringWithFormat: @"%@", [nformat stringFromNumber: [NSNumber numberWithDouble: doubleValue]] ]; 
     NSUInteger stringLen = [stringValue length]; 

     if ([stringValue hasSuffix:@".00"]) 
     {     
      // Remove suffix 
      stringValue = [stringValue substringWithRange: NSMakeRange(0, stringLen-3)];    
     } else if ([stringValue hasSuffix:@".0"]) { 

      // Remove suffix 
      stringValue = [stringValue substringWithRange: NSMakeRange(0, stringLen-2)]; 

     } else if ([stringValue hasSuffix:@"0"]) { 

      // Remove suffix 
      stringValue = [stringValue substringWithRange: NSMakeRange(0, stringLen-1)];   
     } 


     // Add the letter suffix at the end of it 
     stringValue = [stringValue stringByAppendingString: s]; 

     //stringValue = [NSString stringWithFormat: @"%@%@", [nformat stringFromNumber: [NSNumber numberWithDouble: doubleValue]] , s] ; 
     break ; 
    }  
} 

NSLog(@"Cash = %@", stringValue); 

Answer 1

unsigned long long value = 1700llu; 
//value = 32600001llu; 
//value = UINT64_MAX; 

NSUInteger index = 0; 
double dvalue = (double)value; 
//Updated to use correct SI Symbol (http://en.wikipedia.org/wiki/SI_prefix) 
NSArray *suffix = @[ @"", @"k", @"M", @"G", @"T", @"P", @"E" ]; 

while ((value/=1000) && ++index) dvalue /= 1000; 

NSString *svalue = [NSString stringWithFormat:@"$%.*f%@", 
        //Use boolean as 0 or 1 for precision 
        (int)(dvalue < 100.0 && ((unsigned)((dvalue - (unsigned)dvalue) * 10) > 0)), 
        dvalue, [suffix objectAtIndex:index]]; 
NSLog(@"Value: %@", svalue); 

---

ARC本地化版本

unsigned long long value = 1700llu; 
//value = 32600001llu; 
//value = UINT64_MAX; 

NSUInteger index = 0; 
double dvalue = (double)value; 
//Updated to use correct SI Symbol (http://en.wikipedia.org/wiki/SI_prefix) 
NSArray *suffix = @[ @"", @"k", @"M", @"G", @"T", @"P", @"E" ]; 

while ((value/=1000) && ++index) dvalue /= 1000; 

NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init]; 
//Germany Example 
[formatter setLocale:[[NSLocale alloc] initWithLocaleIdentifier:@"de-de"]]; 
//Set fractional digits to 0 or 1 
[formatter setMaximumFractionDigits:(int)(dvalue < 100.0 && ((unsigned)((dvalue - (unsigned)dvalue) * 10) > 0))]; 

NSString *svalue = [[formatter stringFromNumber:[NSNumber numberWithFloat:dvalue]] 
        stringByAppendingString:[suffix objectAtIndex:index]]; 

NSLog(@"Value: %@", svalue); 

Answer 2

如果你想自动调节宽度的字符串，你可以使用：

+(NSString*)numberWithShortcut:(NSNumber*)number 
{ 
    unsigned long long value = [number longLongValue]; 

    NSUInteger index = 0; 
    double dvalue = (double)value; 

    NSArray *suffix = @[ @"", @"K", @"M", @"B", @"T", @"P", @"E" ]; 

    while ((value /= 1000) && ++index) dvalue /= 1000; 

    NSString *svalue = [NSString stringWithFormat:@"%@%@",[NSNumber numberWithDouble:dvalue], [suffix objectAtIndex:index]]; 

    return svalue; 
}