Objective-C > NSString

1. Declare a new NSString object named "str1":

NSString *str1 = [NSString stringWithFormat:@"iPhone Programming is easy];

2. Declare the new NSString object "str1" within "showMessage" method:

3. Build & Run:

<same result>

4. Declare the NSString object "str1" also likes this:

NSString *str1 = @"iPhone Programming is super easy";

5. Build & Run again:
Before click, the original text of label1 is "Hello Nattoise".

After click, the text of label1 is changed to "iPhone Programming is super easy".

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Common class method [ + ] and instance methods [ - ]:

+	stringWithFormat                                <-- Class Method [ + ]
-	stringByAppendingString                    <-- Instance Method [ - ]
-	isEqualToString
-	length
-	intValue
-	floatValue
-	uppercaseString
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-
-
-
-
-
-

+: Class Method: 無須實體化就可以使用的方法 (生仔用only)

-: Instance Method: 需先實體化才可以使用的方法，假設str1 已經是NSString 文字實體 (生完仔, 對仔落指令)

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[+] stringWithFormat: (NSString *) format

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[-] (NSString *) stringByAppendingString: (NSString *) format

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[-] (BOOL) isEqualToString: (NSString *) aString

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[-] (NSUInteger) length

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[-] (NSUInteger) intValue

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[-] (float) floatValue

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[-] (NSString *) uppercaseString

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Reference: https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/Reference/NSString.html