將座標字符串轉換爲浮點型

Question

我想將此格式的字符串座標50.3332W轉換爲等效浮點型表示-50.3332。

目前我有這樣的事情，但它只是取代W字符，並在最後放置減號。

NSString *newtest = [_myTextField.text stringByReplacingOccurrencesOfString:@"W" withString:@"-"]; 

對此的任何幫助將有所幫助。

Answer 1

// *** Your string value *** 
NSString *value = @"50.3332W"; 

// *** Remove `W` from string , convert it to float and make it negative by multiplying with -1. 
CGFloat floatValue = [[value stringByReplacingOccurrencesOfString:@"W" withString:@""] floatValue] * -1; 

// ** Result negative float value without `W` ** 
NSLog(@"%f",floatValue); 

Answer 2

試試這個方法：

- (float)coordinateToFloat:(NSString*)coordinateString { 
    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"(\\d+\\.?\\d+?)(W)" options:NSRegularExpressionCaseInsensitive error:nil]; 
    NSString* preffixString = [regex stringByReplacingMatchesInString:coordinateString options:0 range:NSMakeRange(0, coordinateString.length) withTemplate:@"$2$1"]; 
    NSString* normalizedString = [preffixString stringByReplacingOccurrencesOfString:@"W" withString:@"-"]; 
    return normalizedString.floatValue; 
} 

然後，你可以這樣調用：

[self coordinateToFloat:@"50.3332W"]; // Returns -50.3332 
[self coordinateToFloat:@"50.3332"]; // Returns 50.3332 

Regex Demo