本文共 2350 字，大约阅读时间需要 7 分钟。

下面介绍 UITextView 的字数控制,占位符,以及键盘回退方法.

1.字数控制实现

#import "ViewController.h"#define kScreenWidth [UIScreen mainScreen].bounds.size.width@interface ViewController ()
   
    /** textView */@property (nonatomic, weak) UITextView *textView;/** placeHoldLabel */@property (nonatomic, weak) UILabel *placeHoldLabel;/** noticeLabel */@property (nonatomic, weak) UILabel *noticeLabel;@end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];    UITextView *textView = [[UITextView alloc] initWithFrame:CGRectMake(0, 64, kScreenWidth, 200)]; //初始化大小并自动释放    _textView = textView;    textView.textColor = [UIColor blackColor];//设置字体颜色    textView.font = [UIFont fontWithName:@"Arial" size:18.0];//设置 字体 和 大小    textView.delegate = self;// 设置控制器为 textView 的代理方法    textView.backgroundColor = [UIColor lightGrayColor];//设置它的背景颜色    textView.returnKeyType = UIReturnKeyDefault;//返回键的类型    textView.keyboardType = UIKeyboardTypeDefault;//键盘类型    textView.scrollEnabled = YES;//是否可以拖动    [self.view addSubview:textView];    UILabel *placeHoldLabel = [[UILabel alloc]initWithFrame:CGRectMake(5, 5, kScreenWidth, 25)];    self.placeHoldLabel = placeHoldLabel;    placeHoldLabel.font = [UIFont systemFontOfSize:18];    placeHoldLabel.enabled = NO;    placeHoldLabel.text = @"请输入您的内容...";    placeHoldLabel.numberOfLines=0;    placeHoldLabel.font =  [UIFont systemFontOfSize:12];    [self.textView addSubview:placeHoldLabel];    UILabel *noticeLabel = [[UILabel alloc] initWithFrame:CGRectMake(5, 280, kScreenWidth * 0.95, 20)];    self.noticeLabel = noticeLabel;    noticeLabel.textAlignment = NSTextAlignmentRight;    noticeLabel.text = @"您还可以输入200字!";    [self.view addSubview:noticeLabel];}#pragma mark - 2.textView delegate-(void)textViewDidChange:(UITextView *)textView{    if ([self.textView.text length] == 0) {        [self.placeHoldLabel setHidden:NO];    }else{        [self.placeHoldLabel setHidden:YES];    }}- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text{    if([text isEqualToString:@"\n"]){        [textView resignFirstResponder];        return NO;    }    if (range.location>=200){        self.noticeLabel.text=@"还能输入0字";        return  NO;    } else {        self.noticeLabel.text=[NSString stringWithFormat:@"还能输入%lu字",200-range.location];        return YES;    }}@end
   

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