在Objective-C中有没有(stringByAppendingString:)字符串连接的快捷方式，或者一般使用NSString的快捷方式?
例如，我想做:
NSString *myString = @"This";
NSString *test = [myString stringByAppendingString:@" is just a test"];
更像是:
string myString = "This";
string test = myString + " is just a test";
当前回答
这样使用stringByAppendingString:
NSString *string1, *string2, *result;
string1 = @"This is ";
string2 = @"my string.";
result = [result stringByAppendingString:string1];
result = [result stringByAppendingString:string2];
OR
result = [result stringByAppendingString:@"This is "];
result = [result stringByAppendingString:@"my string."];
其他回答
尝试stringWithFormat:
NSString *myString = [NSString stringWithFormat:@"%@ %@ %@ %d", "The", "Answer", "Is", 42];
NSString *result=[NSString stringWithFormat:@"%@ %@", @"Hello", @"World"];
这样使用stringByAppendingString:
NSString *string1, *string2, *result;
string1 = @"This is ";
string2 = @"my string.";
result = [result stringByAppendingString:string1];
result = [result stringByAppendingString:string2];
OR
result = [result stringByAppendingString:@"This is "];
result = [result stringByAppendingString:@"my string."];
宏:
// stringConcat(...)
// A shortcut for concatenating strings (or objects' string representations).
// Input: Any number of non-nil NSObjects.
// Output: All arguments concatenated together into a single NSString.
#define stringConcat(...) \
[@[__VA_ARGS__] componentsJoinedByString:@""]
测试用例:
- (void)testStringConcat {
NSString *actual;
actual = stringConcat(); //might not make sense, but it's still a valid expression.
STAssertEqualObjects(@"", actual, @"stringConcat");
actual = stringConcat(@"A");
STAssertEqualObjects(@"A", actual, @"stringConcat");
actual = stringConcat(@"A", @"B");
STAssertEqualObjects(@"AB", actual, @"stringConcat");
actual = stringConcat(@"A", @"B", @"C");
STAssertEqualObjects(@"ABC", actual, @"stringConcat");
// works on all NSObjects (not just strings):
actual = stringConcat(@1, @" ", @2, @" ", @3);
STAssertEqualObjects(@"1 2 3", actual, @"stringConcat");
}
备用宏:(如果你想强制一个最小数量的参数)
// stringConcat(...)
// A shortcut for concatenating strings (or objects' string representations).
// Input: Two or more non-nil NSObjects.
// Output: All arguments concatenated together into a single NSString.
#define stringConcat(str1, str2, ...) \
[@[ str1, str2, ##__VA_ARGS__] componentsJoinedByString:@""];
当处理字符串时，我经常发现使源文件objc++更容易，然后我可以使用问题中显示的第二个方法连接std::字符串。
std::string stdstr = [nsstr UTF8String];
//easier to read and more portable string manipulation goes here...
NSString* nsstr = [NSString stringWithUTF8String:stdstr.c_str()];
