NSRange 和 NSString
by Elton on 十二.25, 2009, under Mac
NSRange的定义
1 2 3 4 5 | typedef struct _NSRange { NSUInteger location; NSUInteger length; } NSRange; |
NSRange是一个结构体，其中location是一个以0为开始的index，length是表示对象的长度。他们都是NSUInteger类型。 而NSUInteger类型的定义如下：
1 2 3 4 5 | #if __LP64__ || TARGET_OS_EMBEDDED || TARGET_OS_IPHONE || TARGET_OS_WIN32 || NS_BUILD_32_LIKE_64 typedef unsigned long NSUInteger; #else typedef unsigned int NSUInteger; #endif |
例子：
下面这个例子，将输出IPA
1 2 3 4 5 6 7 8 9 | NSString *homebrew = @"Imperial India Pale Ale (IPA)"; // Starting at position 25, get 3 characters NSRange range = NSMakeRange (25, 3); // This would also work: // NSRange range = {25, 3}; NSLog (@"Beer shortname: %@", [homebrew substringWithRange:range]); |
搜索字符串：
1 2 3 4 5 6 | NSString *homebrew = @"Imperial India Pale Ale (IPA)"; NSRange range = [homebrew rangeOfString:@"IPA"]; // Did we find the string "IPA" ? if (range.length > 0) NSLog(@"Range is: %@", NSStringFromRange(range)); |
上面的程序将输出Range is: {25, 3}。NSStringFromRange()方法，将一个NSRange返回一个NSString。而另外一个函数NSRangeFromString()则是将NSString转换为NSRange
下面这个例子将从后向前反向搜索字符串：
1 2 3 4 5 6 7 8 | NSString *homebrew = @"Imperial India Pale Ale (IPA)"; // Search for the "ia" starting at the end of string NSRange range = [homebrew rangeOfString:@"ia" options:NSBackwardsSearch]; // What did we find if (range.length > 0) NSLog(@"Range is: %@", NSStringFromRange(range)); |
上面的程序将输出：Range is: {12, 2}
Objective-C中没有正则表达式，如果你想使用更复杂的字符串匹配，可以使用这个类库RegexKitLite。它提供了完整的正则表达式实现。
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七月 6th, 2010 on 10:32
Need to subscribe to this blog, great post. Found it on bing.