NSString - 常用方法总结

[color=darkred][size=large]创建字符窜[/size][/color]

[color=green]常量字符窜[/color]

NSString  *str  =  @“str”;

[color=green]创建字符窜方法[/color]

[NSString alloc]init];     //先创建字符窜对象  
str = @"str";    // 再给字符窜对象赋值

[color=green]initWithString创建字符窜[/color]

NSString *str =  [[NSString alloc] initWithString:@"str"]; // 创建对象初始化时,利用构造方法传入字符.

[color=darkred][size=large]格式化创建字符窜[/size][/color]

[color=green]int格式化字符窜[/color]

int age = 20;
NSString *str = [NSString stringWithFormat:@"age is %d",age]; // 拼凑字符窜

[color=green]NSString 格式化字符窜[/color]

NSString *str = @"str";
NSString *str2 = [[NSString alloc] stringWithFormat:@"%@ and str2",str];

[color=darkred][size=large]字符窜比较[/size][/color]

[color=green]isEqualToString方法比较[/color]

NSString  *str  =  @“str”;
NSString  *str2 =  @“str”;

BOOL result = [str isEqualTostring:str2]; // 字符窜的对象方法,参数是另外一个字符窜对象.返回BOOL

[color=green]compare方法比较[/color]

NSString  *str  =  @“str”;
NSString  *str2 =  @“str”;

BOOL result = [str compare:str2]; // 这里返回的是 result == NSOrderedSame 代表完全一致 值为0

compare返回值是 NSComparisonResult ,而这个值是一个枚举
NSOrderedAscending = -1            // 表示左侧小于右侧 ,   值是 -1
NSOrderedSame                            // 代表左右是一模一样的  值是 0
NSOrderedDescending                  // 表示左侧大于右侧  值是 1


[str compare:str2 options:]

[color=darkred][size=large]字符窜大小写转换[/size][/color]


[color=green]小写转大写[/color]

NSString *str =@"str";
[str lowercaseString]; //返回STR

[color=green]大写转小写[/color]

NSString *str =@"sTr";
[str uppercaseString]; //返回str

[color=darkred][size=large]截取字符窜[/size][/color]

[color=green]subStringToIndex截取字符窜[/color]

NSString *str =@"str";
[str subStringToIndex:1]; == "s"

[color=green]subStringFromIndex截取字符窜[/color]

NSString *str =@"str";
[str subStringFromIndex:1]; == "tr"

[color=green]subStringWithRange截取字符窜[/color]

NSString *str =@"str";
[str subStringWithRange:NSMakeRange(1,2)]; // == "tr" 从第一个开始取，取两个

[color=darkred][size=large]判断字符窜是否包含另一个字符窜[/size][/color]

NSString *str1 =@"1 str1";
NSString *str2 =@"str";

NSRange  range  = [str1 rangeOfString:str2];

NSInteger location = range.location; // 2 str2包含在第二个位置 
NSInteger leight = range.length; //  字符长度3