Objective-C

NSString *string = @"123";

// 1.字符串转int
int intString = [string intValue];

// 2.int装字符串
NSString *stringInt = [NSString stringWithFormat:@"%d",intString];

// 3.字符串转float
float floatString = [string floatValue];

// 4.float转字符串
NSString *stringFloat = [NSString stringWithFormat:@"%f",floatString];