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How to understand copy and mutableCopy in OC? I believe many inexperienced people don't know what to do about it. Therefore, this paper summarizes the causes and solutions of the problem. Through this article, I hope you can solve this problem.

In OC, there are two types of replication: copy and mutableCopy. As the name implies, it generates immutable or mutable objects. Please refer to the code as to whether the copied object is the new object or the original object:

# import int main (int argc, char * argv []) {@ autoreleasepool {NSString * S1 = @ ""; NSString * S2 = [S1 copy]; NSMutableString * S3 = [S1 mutableCopy]; NSString * S4 = [S3 copy]; NSLog (@ "S1 addr =% p", S1) NSLog (@ "S2 addr =% p", S2); NSLog (@ "S3 addr =% p", S3); NSLog (@ "S4 addr =% p", S4);}}

The result of the output is:

S1 addr = 0x10a2e6030

S2 addr = 0x10a2e6030

S3 addr = 0x7fd0b940c6e0

S4 addr = 0x6168616845

Thus, copy operations on immutable objects do not produce new objects, but point to the original objects. The rest will generate a new copy.

CopymutableCopy mutable object

New object New object immutable object original object New object after reading the above, have you mastered the method of how to understand copy and mutableCopy in OC? If you want to learn more skills or want to know more about it, you are welcome to follow the industry information channel, thank you for reading!

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