Question

objective c的字符串变量怎么定义

Answer 1

可以用NSMutableString

例如：
NSMutableString * str = [[NSMutableString alloc] initWithCapacity:128];

下面是苹果公司网站上查到的用法：
（链接：https://developer.apple.com/library/ios/documentation/Cocoa/Reference/Foundation/Classes/NSMutableString_Class/index.html#//apple_ref/occ/instm/NSMutableString/initWithCapacity:）

Returns an NSMutableString object initialized with initial storage for a given number of characters,

Declaration

Swift

init(capacity capacity: Int)

Objective-C

- (NSMutableString *)initWithCapacity:(NSUInteger)capacity

Parameters

capacity

The number of characters the string is expected to initially contain.

Return Value

An initialized NSMutableString object with initial storage for capacity characters. The returned object might be different than the original receiver.

Discussion

The number of characters indicated by capacity is simply a hint to increase the efficiency of data storage. The value does not limit the length of the string.

Answer 2

C风格字符串 char* str1 = "123456";
ObjC风格字符串 NSString* str2 = @"123456" ; @的含义和C++中的L差不多。

NSString的函数里面可以支持上述两个相互转换。