字符串轉換爲Double外幣

Question

NSNumberFormatter *numberFormatter = [[NSNumberFormatter alloc] init]; 
    [numberFormatter setNumberStyle: NSNumberFormatterCurrencyStyle]; 
    double value = [[numberFormatter numberFromString: ProviderTripRate.text] doubleValue]; 
    [User setDouble:value forKey:@"Trip_Rate"]; 
NSLog(@"  %@     %f  " , ProviderTripRate.text , value ); 

如果內部ProviderTripRate.text的數據是2.75，然後爲0錯誤 如果內部ProviderTripRate.text數據爲$ 2.75則值2.75正確

你如何可靠地轉換從字符串到雙精度值 注意，文本字符串可能會或可能不會對當地貨幣符號（$如上所示） 但應該有轉換

在此先感謝

Answer 1

試試這個：

if ([providerTripRate.text hasPrefix:@"$"]) { 
    // use NSNumberFormatter to obtain the value 
} else { 
    float theValue = [providerTripRate.text doubleValue]; 
} 

等

Answer 2

試試這個：

NSNumberFormatter *numberFormatter = [[NSNumberFormatter alloc] init]; 
[numberFormatter setNumberStyle: NSNumberFormatterCurrencyStyle]; 
NSNumber* number = [numberFormatter numberFromString:ProviderTripRate.text] 
if (!number) { 
    [numberFormatter setNumberStyle: NSNumberFormatterDecimalStyle]; 
    number = [numberFormatter numberFromString:ProviderTripRate.text]; 
} 
double value = [number doubleValue]; 

Answer 3

extension String { 
/// Creates a Double from the string 
/// 
/// Tries various ways of extracting a number, currently handling the following formats 
/// - 1000 
/// - 1000.00 
/// - 1,000.00 
/// - $1,000.00 
/// 
/// - Returns: Double value, or 0.0 if a non numerical String is passed 
    func asDouble() -> Double { 

    if let double = Double(self) { 
     return double 
    } 

    let formatter = NumberFormatter() 
    if let number = formatter.number(from: self) { 
     return number.doubleValue 
    } 

    formatter.numberStyle = .currency 
    if let number = formatter.number(from: self) { 
     return number.doubleValue 
    } 

    formatter.currencySymbol = "" 
    formatter.internationalCurrencySymbol = "" 

    if let number = formatter.number(from: self) { 
     return number.doubleValue 
    } 

    return 0 
    } 
}