[Objective-c] Stringに関して

Strings

1.Creating Strings

NSString* aString = [[NSString alloc] init];
NSString* aString = @"Hello, world!";

NSInteger sizeOfString = [@"Hello, world!" length];

2.Capitalization and working with paths

NSString* originalString = @"This is An EXAMPLE";

// "THIS IS AN EXAMPLE"
NSString* upperCaseString = [originalString uppercaseString];

// "this is an example"
NSString* lowerCaseString = [originalString lowercaseString];

// "This Is An Example"
NSString* capitalizedString = [originalString capitalizedString];

3.Finding substrings

NSString* startSubstring = [originalString substringToIndex:5]; // "This "
NSString* endSubstring = [originalString substringFromIndex:5]; // "is An EXAMPLE"

NSRange theRange = NSMakeRange(2, 5);
NSString* substring = [originalString substringWithRange:theRange]; // "is is"

4.Comparing Strings

if(firstString == secondString) {
// Do something
}

if ([firstString isEqualToString:secondString]) {
// Do something
}

5.Searching Strings

NSString* sourceString = @"Four score and seven years ago";
NSRange range = [sourceString rangeOfString:@"seven"];

if (range.location == NSNotFound) {
// the string was not found
} else {
// the string was found; 'range' variable contains info on where it is
}

NSRange range = [sourceString rangeOfString:@"SEVEN" options:NSCaseInsensitiveSearch];

6.Arrays

NSArray* myArray = @[@"one, @"two", @"tree"];
NSString* oneString = myArray[0];
NSString* twoString = myArray[1];

NSString* oneString = [myArray objectAtIndex:0];
int count = myArray.count;
int index = [myArray indexOfObject:@"two"]; // should be equal to 1
if (index == NSNotFound) [
NSLog(@"Couldn't find the object!");
}

NSRange subArrayRange = NSMakeRange(1,2);
NSArray* subArray = [myArray subArrayWithRange:subArrayRange];

//subArray now contains "two", "three"

7.Fast Enumeration

for (NSString* string in myArray) {
// this code is repeated 3 times, one for each item in the array
}

8.Mutable Arrays

NSMutableArray* myArray = [NSMutableArray arrayWithArray:@[@"One", @"Two"]];

// Add "Three" to the end
[myArray addObject:@"Three"];

// Add "Zero" to the start
[myArray insertObject:@"Zero" atIndex:0];

// The array now contains "Zero", "One", "Two", "Three".

[myArray removeObject:@"One"]; // removes "One"
[myArray removeObjectAtIndex:1]; // removes "Three", the second

// The array now contains "Zero","Three"

[myArray replaceObjectAtIndex:1 withObject:@"One"]; // myArray is now "Zero", "One"

9.Dictionaries

NSDictionary* translationDictionary = @{
@"greeting": @"Hello",
@"farewell":@"Goodbye"
};

NSDictionary* translationDictionary = @{@"greeting" : @"Hello"};
NSString* greeting = translationDictionary[@"greeting"];

// Here, aDictionary is an NSDictionary
for (NSString* key in aDictionary) {
NSObject* theValue = aDictionary[key];
// do something with theValue
}

NSMutableDictionary* aDictionary = @{};
aDictionary[@"greeting"] = @"Hello";
aDictionary[@"farewell"] = @"Goodbye";

10.NSValue and NSNumber

NSNumber* theNumber = @123;
int myValue = [theNumber intValue];

int a = 100;
NSNumber* number = @(a+1); // 'number' contains 101