按首字符的大小，进行字符串排序

<pre name="code" class="objc">////  main.m//  按首字符的大小，进行字符串排序////  Created by SUN on 16/7/30.//  Copyright © 2016年 VitoSun. All rights reserved.//#import <Foundation/Foundation.h>int main(int argc, const char * argv[]) {    @autoreleasepool {        NSMutableArray *array = [NSMutableArray arrayWithObjects:@"sda",@"tew",@"rtgfd",@"fg", nil];        for (int i= 0; i<array.count-1; i++) {            for (int j= 0; j<array.count-1-i; j++) {                if([array[j] characterAtIndex:0]>[array[j+1] characterAtIndex:0]){                    [array exchangeObjectAtIndex:j withObjectAtIndex:j+1];                }            }        }        [array enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {            NSLog(@"%@",obj);        }];    }    return 0;}