-[__NSCFConstantString size]: unrecognized selector sent to instance 0x10ecaf248

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFConstantString size]: unrecognized selector sent to instance 0x10ecaf248'

错误原因:

NSArray *images = @[@"1",@"1",@"1",@"1"];

UIImage *image = images[i];