在 Objective-C 中连接不确定字符串的有效方法

Question

如果变量不是 nil，我想从变量中连接一些字符串。 如果它们为零，我不想包括它们。 以下代码有效，但很笨拙，并且随着其他变量的增加而按比例变得更加复杂。谁能推荐一种更优雅的方式来做到这一点？

NSString *city = self.address.city== nil ? @"" : self.address.city;
NSString *state = self.address.state== nil ? @"" : self.address.state;
NSString *zip = self.address.zip== nil ? @"" : self.address.zip;
NSString *bestCity;
if (city.length>0&&state.length>0&&zip.length>0) {
     bestCity = [NSString stringWithFormat: @"%@ %@ %@", city, state,zip];
}
else if (city.length>0&&state.length>0) {
    bestName = [NSString stringWithFormat: @"%@ %@", city,state];
}
else if (city.length>0&&zip.length>0) {
    bestCity = [NSString stringWithFormat: @"%@ %@", city,zip];
}
else if (city.length>0&&zip.length>0) {
    bestCity = [NSString stringWithFormat: @"%@ %@", city,zip];
}
else if (city.length>0) {
    bestCity = [NSString stringWithFormat: @"%@", city];
}
else if (state.length>0) {
    bestCity = [NSString stringWithFormat: @"%@", state];
}
else if (zip.length>0) {
    bestCity = [NSString stringWithFormat: @"%@", zip];
}
else {
    bestCity = @"";
}

Answer 1

我通常会做这样的事情：

NSMutableArray *bestCityArr = [@[] mutableCopy]; // [[NSMutableArray alloc] init];
if (city.length > 0)
    [bestCityArr addObject:city];
if (state.length > 0)
    [bestCityArr addObject:state];
if (zip.length > 0)
    [bestCityArr addObject:zip];
NSString *bestCity = [bestCityArr componentsJoinedByString:@" "];

Answer 2

NSMutableArray *items = [[NSMutableArray alloc] init];
if (self.address.city)
    [items appendObject:self.address.city];
if (self.address.state)
    [items appendObject:self.address.state];
if (self.address.zip)
    [items appendObject:self.address.zip];
NSString *bestCity = [items componentsJoinedByString:@" "];

Answer 3

这段代码可能会对你有所帮助！

- (NSString *)concatenateString
{
    NSMutableString *bestCity = [NSMutableString string];
    NSString *city = self.address.city ?: @"";
    [bestCity appendString:city];
    NSString *state = self.address.state ?: @"";
    if (state.length > 0) {
        [bestCity appendString:@" "];
    }
    [bestCity appendString:state]];
    NSString *zip = self.address.zip ?: @"";
    if (zip.length > 0) {
        [bestCity appendString:@" "];
    }
    [bestCity appendString:zip];
    return bestCity.length > 0 ? bestCity : @"";
}